ASSESSMENT OF PHYSICO-CHEMICAL AND MICROBIOLOGICAL PROPERTIES OF SHALLOW WELL WATER IN KAWANGWARE LOCATION, NAIROBI CITY COUNTY, KENYA
BETH WAITHERA NJIRAINI (N50/CE/26874/2011)
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF MASTER OF ENVIRONMENTAL SCIENCE IN THE SCHOOL OF ENVIRONMENTAL STUDIES OF KENYATTA UNIVERSITY
SEPTEMBER, 2020 DECLARATION
This research project is my original work and has not been presented for a degree in any other university or for any other award
Signature: …………………………………. Date: ………………………………… Beth Waithera Njiraini N50/CE/26874/2011)
SUPERVISORS
We confirm that the work reported in this thesis was carried out by the candidate under our supervision
Signature: …………………………………. Date: ………………………………… Dr. Gladys Gathuru Department of Environmental Science Kenyatta University
Signature …………………………………. Date ………………………………… Dr. Ezekiel Ndunda Department of Environmental Science Kenyatta University
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DEDICATION
This thesis is dedicated to: My husband, Andrew and my sons; Joseph, Denzel and Ethan for their support during the course of my studies.
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ACKNOWLEDGEMENT
Over and above everything, praise is to the Almighty Jehovah God for the great plans He has for me. Special appreciation go to my supervisors Dr. Gladys Gathuru and Dr.
Ezekiel Ndunda for their tireless supervision and guidance that helped me to remain focused on my topic in due course gathering so much knowledge. Special thanks to Mr.
Alaro, Mr Nganga and Ms Lillian, Technician in the Microbiology Department Kenyatta
University, Ken Kirel, Benjamin Gichohi, and Mathew Theuri Technician in Kenyatta
University Environmental Science laboratory for their overwhelming support.
I would also like to recognize Mr. Mungai and Cleopas Munene in assisting me in identify sampling point in the field and without them accessing these sampling locations would not have been possible. Finally, I wish to appreciate my friends Madam Racheal
Atieno from Water Resource Management Authority (WRMA) and Peter Kamande in the
Masters class for their encouragement and support. God bless you all.
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TABLE OF CONTENTS
DECLARATION...... ii
DEDICATION...... iii
ACKNOWLEDGEMENT ...... iv
TABLE OF CONTENTS ...... v
LIST OF TABLES ...... ix
LIST OF FIGURES ...... x
ABBREVIATIONS AND ACRONYMS ...... xi
ABSTRACT ...... xii
CHAPTER ONE: INTRODUCTION ...... 1
1.1 Background to the Study ...... 1
1.2 Statement of the problem ...... 4
1.3 Objectives of the Study ...... 5
1.3.1 Overall Objective ...... 5
1.3.2 Specific Objectives ...... 6
1.4 Research Hypotheses ...... 6
1.5 Conceptual Framework ...... 6
1.6 Scope and Justifications ...... 8
1.7 Definition of Terms...... 9
CHAPTER TWO: LITERATURE REVIEW ...... 10
2.1 Ground Water...... 10
2.2 Shallow Wells Pollution ...... 12
2.3 Physico-chemical properties of groundwater ...... 15
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2.3.1 Turbidity ...... 16
2.3.2 Total dissolved solid ...... 17
2.3.3 pH ...... 17
2.3.4 Temperature ...... 18
2.3.5 The electrical conductivity ...... 19
2.3.6 Total hardness ...... 19
2.3.7 Sulphates ions ...... 20
2.3.8 Nitrates ions ...... 20
2.2.9 Phosphate ions ...... 21
2.3.10 Lead ions ...... 21
2.3.11 Iron ions ...... 22
2.3.12 Cadmium ions ...... 22
2.3.13 Zinc ions...... 23
2.3.14 Sodium ions ...... 23
2.3.15 Potassium ions ...... 23
2.4 Indicator micro-organisms ...... 23
2.4.1 Total coliform bacteria (TC) ...... 24
2.4.2 Faecal coliform bacteria (FC) ...... 24
2.5 Water quality and Sanitation in relation to waterborne diseases ...... 25
2.5.1 Diarrheal Disease ...... 26
2.5.2 Cholera ...... 26
2.5.3 Bacillary dysentery (Shigellosis) ...... 27
2.5.4 Typhoid fever ...... 27
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2.6 Gaps Identified in literature ...... 28
CHAPTER THREE: RESEARCH METHODOLOGY ...... 29
3.1 Overview ...... 29
3.2 General information of the study area ...... 29
3.3 The Design of the Study ...... 32
3.4 Sampling and Sampling procedure ...... 32
3.4.1 Sample Selection and Sample Size...... 32
3.4.2 Sampling procedure ...... 33
3.5 Physico-chemical Analysis ...... 33
3.5.1 In-situ measurements ...... 34
3.5.2 Laboratory analysis for chemical analysis ...... 35
3.5.3 Total metal determination using atomic absorption spectrophotometer (AAS) ...... 37
3.5.4 Microbiological Analysis ...... 38
3.6 Data Analysis ...... 39
CHAPTER FOUR: RESULTS AND DISCUSSION ...... 40
4.1 Introduction ...... 40
4.2 Physico-chemical parameters of groundwater used by household in Kawangware ... 40
4.2.1 Temperature ...... 43
4.2.2 pH ...... 44
4.2.3 Electrical conductivity ...... 45
4.2.4 Turbidity ...... 46
4.2.5 Total Dissolved Solids ...... 47
4.2.6 Total Hardness ...... 48
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4.2.7 Sulphate...... 49
4.2.8 Nitrate ...... 49
4.2.9 Phosphate ...... 50
4.2.10 Iron ...... 51
4.2.11 Lead...... 53
4.2.12 Cadmium ...... 54
4.2.13 Zinc ...... 55
4.2.14 Sodium ...... 55
4.2.15 Potassium ...... 56
4.3 Microbiological properties of shallow water wells used in Kawangware location .... 58
CHAPTER FIVE: SUMMARY, CONCLUSIONS AND
RECOMMENDATIONS ...... 61
5.1 Summary ...... 61
5.2 Conclusions ...... 61
5.3 Recommendations ...... 62
5.4 Future Research ...... 62
REFERENCES ...... 63
APPENDICES ...... 71
Appendix I: KEBS Potable Water Standard ...... 71
Appendix II: Authorization letter from the university ...... 72
Appendix III: Authorization letter from Ministry of Devolution and Planning ...... 73
Appendices IV: NACOSTI Letter ...... 74
Appendix V: Raw Data for Kawangware Location ...... 75
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LIST OF TABLES
Table 4.1: Physico-chemical parameters of groundwater for Kabiro site ...... 40
Table 4.2: Physico-chemical parameters of ground for Kawangware site ...... 41
Table 4.3: Physico-chemical parameters of ground for Gatina site ...... 42
Table 4.4: Comparison of the total coliform in shallow wells water located in Kabiro,
Kawangware and Gatina locations...... 58
Table 4.5: Comparison of the faecal coliform in shallow wells water located in
Kabiro, Kawangware and Gatina locations ...... 58
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LIST OF FIGURES
Figure 1.1: Conceptual framework ...... 7
Figure 3.1: Map of Kawangware location showing sampling sites...... 31
Figure 4.1: Mean temperatures of the shallow well water in Kawangware location ...... 43
Figure 4.2: Mean pH levels of the shallow well water in Kawangware location ...... 44
Figure 4.3: Mean Electrical conductivity of the shallow well water in Kawangware
location ...... 45
Figure 4.4: Mean turbidity levels of the shallow well water in Kawangware location .....46
Figure 4.5: Mean total dissolved solids of the shallow well water in Kawangware
location ...... 47
Figure 4.6: Mean total hardness of the shallow well water in Kawangware location ...... 48
Figure 4.7: Mean Nitrate of the shallow well water in Kawangware location ...... 50
Figure 4.8: Mean phosphate levels of the shallow well water in Kawangware location ...51
Figure 4.9: Mean Iron levels the shallow well water in Kawangware location ...... 52
Figure 4.11: Mean cadmium levels of the shallow well water in Kawangware location ..54
Figure 4.12: Mean Sodium levels of the shallow well water in Kawangware location.....56
Figure 4.13: Mean potassium levels of the shallow well water in Kawangware location .57
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ABBREVIATIONS AND ACRONYMS
APHA American Public Health Association
BGS British Geological Survey
EC Electrical Conductivity
EDTA Ethylene Diamine Tetra Acetic Acid
GOK Government of Kenya
KEBS Kenya Bureau of Standards
MDGs Millennium Development Goals
NCWSC Nairobi city water and Sewerage company
NEMA National Environment Management Authority
TDS Total Dissolved Solids
UN United Nations
UNEP United Nations Environment Program
UNESCO United Nations Educational, Scientific and Cultural Organization
WHO World Health Organization
WRMA Water Resources Management Authority
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ABSTRACT
Lack of access to clean drinking water adversely the public health. Kawangware location is undergoing rapid expansion in population, economic growth and urbanization. One of the challenges of this growth is pressure on public water supply. The inconsistent and inadequate water supply for the inhabitants has led to majority of the population relying on ground water for domestic and commercial uses more so, on shallow wells which seem to be relatively cheaper to construct. This has increased the vulnerability of underground water sources to sewage and waste water contamination and therefore exposing the population to infections by various water borne pathogens such as bacteria, viruses and protozoa. The aim of this study was to determine the quality of shallow well water used by households in Kawangware Location and compare it with the Kenya Bureau of Standards for drinking water. Water samples were from the three sub-location that is Kabiro, Gatina and Kawangware. Cross-sectional Survey research design was used and was accompanied by laboratory tests to analyze the level of each parameter from twenty eight shallow wells. A total of 112 samples were collected. Water samples were collected in the morning and evening in the month July and August 2017.The collected samples were analyzed for temperature using a mercury thermometer; pH, electrical conductivity, turbidity and Total dissolved solids was determined using portable meters. Zinc, iron, cadmium and lead were analyzed using Atomic Absorption Spectrophotometer, potassium and sodium using a flame photometer, total hardness was analyzed using titration, nitrates, phosphate, and bacteriological analysis were tested in accordance with the Standard methods for the Examination of water and waste waters. Derived values of tables and graphs were adopted for data presentation. The measurements physico-chemical parameters were as follows: in Gatina all parameters were within KEBs drinking water standards except for turbidity value which ranged - 2- from 0.6-78 μS/cm, NO3 value ranged from 17- 19.5 mg/L,PO3 ranged from 0.02- 15.8mg/L, Cd ranged from 0.03-0.06 mg/L and Pb ranged from 0.01-1 mg/L. In Kawangware site all the parameters were within KEBs drinking water standards except - for turbidity value which ranged from 0.0-50.1 μS/cm, NO3 value ranged from 17.5- 2- 19.7mg/L,PO3 ranged from 0.02-42.8 mg/L, Cd ranged from 0.03-0.05 mg/L and Pb ranged from 0.06-0.09 mg/L. In Kabiro site all the parameters were within KEBs drinking water standards except for turbidity value which ranged from 0.0-100.9 μS/cm - 2- ,NO3 value ranged from 14.3-20.1 mg/L,PO3 ranged from 0.04-14.0 mg/L and Cd ranged from 0.03-0.06 mg/L.The result obtained for the microbial analysis indicated that all the water samples analysed from the shallow wells in Kawangware location were contaminated with both total coliform and faecal coliforms. The highest counts of total coliform was 1637 MPN/100 ml and was recorded at Kabiro whilst the lowest counts of 1013 MPN/100 ml was recorded at Kawangware. At the same time, the water from all the sub-location had faecal coliforms with Gatina sub-location recording higher numbers (434 MPN/100 ml) followed by Kawangware (298 MPN/100) and finally Kabiro (271 MPN/100 ml). The results of the study also revealed that the physico-chemical parameters of ground water were significantly different (P≤0.05) from the recommended levels by the KEBS (2010).Parameters like Nitrates, phosphates, turbidity, lead, cadmium, coliforms levels and feacal coliforms exceeded the KEBS standards with the rest being within the acceptable levels. The difference was not significant (p≤ 0.05) between the levels of turbidity, Iron and phosphates and that of KEBS. The ground water in the area is not safe for drinking due to elevated levels of Nitrates, phosphates, turbidity, lead, cadmium, total coliforms levels and feacal coliforms which poses a great health risk to the public therefore there is need to supply safe water for domestic purposes.
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CHAPTER ONE: INTRODUCTION
1.1 Background to the Study
The importance of water for the survival of plants and animals cannot be underrated. It is notable that water is at the core of sustainable development and plays a crucial role as far as energy and food production, socio-economic development, healthy ecosystems and human health is concerned. However, access to clean water remains a major challenge, thus forcing many people to device ways in which they can be able to acquire this noble commodity (Alves, Latorre, McCleod, Payen, Roaf, Rouse, 2016; WHO, 2019). As at
2019, 2.2 billion people lacked access to safely managed drinking water services while over 4.2 billion people failed to have a managed sanitation services (WHO, 2019). There are notable reasons why there has been deficiency in clean water and sanitation in various parts of the world. One of it is lack of infrastructure and poor management of services where governments lack to develop sustainable water supplies and infrastructure. Poverty and inequality as people are unable to access the services due to their social status, ethnicity, gender as well as inability to afford the high costs. Other reasons include population growth where the world’s population is expected to grow to 9.7 billion by
2050 and climate change among other notable factors. However, it is notable that developing countries are the most affected by water shortage, poor quality water and flooding, as about 80% of illnesses in these countries are linked to sanitation and water
(WWAP, 2019). Lack of sanitation and water stress disproportionately affects girls and women as they are they are mainly the primary managers of natural resources in particular small-scale agriculture and household use (Ritter, 2019).
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As a result of the adverse water scarcity, over 144 million people are dependent on surface water in developing countries, and this type of water is prone to contamination, thus making it not a safe for commercial and domestic use (WHO, 2019). The use of shallow ground water sources for drinking as well as other domestic purposes is thus a common feature for many low income communities in developing countries. In this case, a well is sunk for about 15 meters from which the water is extracted as needed. Shallow wells are relatively cheap to build and maintain since most of them are hand dug and do not go deeper into the ground as compared to boreholes (Terngu, Hyacinth & Rufus,
2010; WaterAid, 2013). In most of the countries in the Middle East and North African region, dependency on surface, shallow wells and groundwater has led to massive depletion of groundwater, thus making it hard for people to access water for domestic and agricultural use. This trend has been replicated in majority of cities in the world most of which are from the developing world (Cronin, et al., 2007). However, it is notable that due to the nature of the construction of shallow well, they are often at risk of contamination.
In Kenya, the issue of ensuring sustainable provision of water and sanitation remains a pipe dream to many across the country, and this is despite it being one of the vision 2030 goals (Tibatemwa, 2017). It is notable that the water scarcity in Kenya is exuberated by increase in population growth in the recent past coupled by many years of recurrent droughts, climate change, poor management and conservation practices of the available water resources to prevent contamination (Tibatemwa, 2017). With most of the Kenyans only having access to polluted water, the issue of waterborne diseases is far from being
2 eliminated. Such diseases like diarrhoea, cholera epidemics and multiple other diseases affect health and livelihoods. By 2018, it is notable that about 80% of people who attended hospitals in Kenya were diagnosed with preventable diseases, while 50% of these illnesses are water, sanitation and hygiene related (UNICEF, 2020).
However, the issue of poor sanitation and water scarcity is more prevalent in cities and towns such as Nairobi, Mombasa, Kisumu and Nakuru among others. According to the
World Bank (2020), in Nairobi, only 40% of the population has access to sewerage system and as the city continues to grow, higher number of the dwellers in Nairobi will be forced to live in low-income settlements, thus making them to live in areas where sanitation and water is a problem. As result, the number of water borne diseases in
Nairobi will continue to increase in areas such as Huruma, Kayole, Matopeni, Dandora,
Kawangware and Githurai will continue unless immediate remedies are taken by the government and stakeholders (World Bank, 2020).
In Kawangware, one of the major towns in Nairobi, the issue of water scarcity and sanitation remains a major problem. According to 2019 national census, the area is highly populated with about 291,565 people residing in the town, majority of who earns lives on less than $1 a day due to high level of unemployment. As result of this, Kawangware has adverse scarcity of safe drinking water as water supplied by the Nairobi City Council is inadequate or otherwise expensive (Kenya National Bureau of Statistics, 2019). The scarcity has resulted to increased number of waterborne diseases, malaria, respiratory pneumonia among other disease associated with poor sewerage system. It is due to the
3 water shortage that dwellers in this area have depended on shallow wells to cater for their daily water needs, thus further exposing them to possible water contamination
(Kinyanjui, 2014). It is based on this study that aims at critically evaluating the quality of groundwater quality in Kawangware location, Nairobi. This study will evaluate the quality of water in shallow wells in three sub-locations namely Kabiro, Gatina and
Kawangware. Although several studies have been carried on the area regarding the quality of groundwater in the Kawangware area, few studies have focused on water accessed from shallow wells and thus this study aims to fill this gap.
1.2 Statement of the problem
Despite the clear benefits of improved sources of potable water for human health and development, many developing countries including Kenya seem to allocate meager resources to meet the sustainable development goals (SDGs) target on clean water and sanitation management. There are also great inequalities in access to clean water and sanitation (UNEP, 2009). According to WHO and UNICEF, as at 2019, only 59% of
Kenyans have access to basic water services and only 29% have access to sanitary services (UNICEF, 2020). This fact is supported by Water.org (2020) who indicated that
41% of the population in Kenya depends on unimproved sources of water which includes rivers and shallow wells. This challenge is more prevalent in urban slums and rural areas
(Water.org, 2020). In Nairobi, 50% of the 4.5 million residents lack access to piped water supplied by the NCWSC (BBC News, 2019). As a result of insufficient water for households by the NCWSC, most households in urban slums such as Kawangware depends on hand dug wells and borehole for drinking water and for other purposes.
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Consequently, the number of the waterborne diseases has been on the rise, in
Kawangware and other slum areas in Nairobi. For example, according to the WHO and
UNICEF joint report in 2012, 60% of all consultations taking place in urban slums in
Nairobi resulted from poor hygiene and sanitation diseases. Further hygiene, water and sanitation related conditions and illnesses accounted for 20% of deaths among children under the age of five years in these areas (UNICEF, 2020). Therefore, it is imperative to closely monitor the quality of ground water in the urban slums to ascertain whether they are safe for drinking. Moreover the water quality parameters of three urban slums have not been extensively studied and hence the types and levels of pollutants are unknown.
With ground water quality data, water quality regulations can be formulated to curb water contamination. Based on this, the study focused on the physico-chemical properties and the microbiological qualities of shallow well water used by households in Kawangware location. The information obtained was then compared to the KEBS standards for each of the selected parameter.
1.3 Objectives of the Study
1.3.1 Overall Objective
The overall objective of this study was to determine the quality of shallow well water used by households in Kawangware area and to ascertain if it is within and KEBS drinking water standards.
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1.3.2 Specific Objectives
i. To analyze the physico-chemical characteristics (temperature, pH, conductivity(
+ + 3+ 2+ 2- EC), total dissolved solids, turbidity, Na ,K , Fe , Zn , CaCO3, SO4 ,
3- 2+ 2+ NO3,PO4 , Cd and Pb ) of shallow well water used by households in
Kawangware location relationship to the KEBS (2010) drinking water standards.
ii. To determine the microbiological characteristics (total coliforms, faecal coliform)
of shallow well water used by households in Kawangware location in relationship
to the KEBS (2010) drinking water standards.
1.4 Research Hypotheses
i. The physico-chemical characteristics (temperature, pH, conductivity( EC), total
+ + 3+ 2+ 2- 3- 2+ dissolved solids, turbidity, Na , K , Fe , Zn , CaCO3, SO4 , NO3,PO4 , Cd
and Pb2+) of shallow well water used by households in Kawangware location are
in variance with the KEBS (2010) drinking water standards.
ii. There is a significant difference between the microbiological characteristics (total
coliforms, faecal coliform) of shallow well water used by households in
Kawangware location with the KEBS (2010) drinking water standards.
1.5 Conceptual Framework
Urbanization, intensive agriculture, industrialization and population increase represent the human activities (drivers) which bring about effects of pollutions to ground water.
The inconsiderate use of fertilizers, leads to nitrate pollution and increase in levels of phosphorus compounds in ground waters. Lack of direct control by the state on the use
6 amounts of fertilizers and pesticides, brings about water contamination (pressures). Poor solid waste management results to bacterial contamination of the water and the physical wastes which get into the source. An industrial discharge to the environment is another menace to the groundwater state. This results to contamination of the ground water which eventually brings about a change in the state of water. If this is not controlled, then it ends up causing water borne diseases (outcomes) to the users and if well controlled then the diseases are averted.
Figure 1.1: Conceptual framework
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1.6 Scope and Justifications
It is notable that the problem of water shortage and poor sanitation is most apparent in urban slum areas of Nairobi. In this regard, majority of the urban dwellers in these areas are forced to get water from unreliable sources such as from kiosks, vendors, through illegal connections and shallow wells among others where the water costs more than 10 times the normal cost of piped water offered by the NCWSC. As result of this, the quality of the water supplied cannot be relied on and considered to be a major cause of waterborne related illnesses. Therefore, this study filled this gap by evaluating the physico-chemical properties and the microbiological qualities of shallow well water used by households in Kawangware location. The research outcomes act as a guide to the policy makers in the water and health sector to find solutions for the residents and to the people of Kawangware. Further, the outcome will act as an eye opener to the residents regarding the quality of shallow well water used in Kawangware location. In this study, a total of 28 shallow wells were used as representative samples and was based on three sites that is Kabiro, Kawangware and Gatina with 7, 8 and 13 wells respectively. The wells considered in this case were the ones that continuously serve as the source of water for daily use by the residents.
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1.7 Definition of Terms
i. Shallow Well: Shallow or unconfined wells are completed in the uppermost
saturated aquifer at that location (the upper unconfined aquifer) (Sara, 2003).
ii. Ground water: This is the water found beneath the surface and can only be utilized
after abstraction (Siebert , et al., 2010). iii. Indicator bacteria: These are types of bacteria whose presence in water is an
indication of fecal contamination. Though not dangerous to human health, they are
an indication of the presence of disease causing microorganisms and thus a health
risk (Myers, 2003). iv. Water quality: This is the condition of water as concerns the physical, chemical,
and biological characteristics relative to the requirements of any human need or
purpose. (Muhammad, et al., 2013).
v. Waterborne diseases: Diseases caused after drinking contaminated water which
contain pathogenic microorganisms (Gray , 2008).
vi. Water Quality Standards Water quality standards (WQS) are standards which form
the legal basis for controlling the pollution levels in water from various sources such
as industrial facilities, storm sewers and wastewater treatment plants. The Guideline
for Drinking-water Quality (GDWQ) from WHO include the recommended limits on
naturally occurring constituents that may have direct adverse effects to health
(United States Environmental Protection Agency, 2018). In Kenya, the KEBS (2010)
recommended standards for drinking water are used.
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CHAPTER TWO: LITERATURE REVIEW
2.1 Ground Water
Water is an important natural resource for supporting and maintaining life in our earth.
Even though 78% of our planet is covered by water, 97% exists in Oceans, is salty and hence not suitable for domestic and industrial use. Only 3% is fresh and suitable for drinking wherein 2.97% is comprised by ice caps and glaciers, the remaining percentage, about 0.3% being available as ground and surface water (Muhammad, et al., 2013).
According to Khublaryan. (2009), groundwater can be described as the water existing in terrestrial crust thickness in all physical states, massif-crystal rock fractures and sediment rock layers. In this regards, groundwater is estimated that 23.4 cubic kilometers, and accounts for 65% of all surface water. Groundwater is efficiently exchanged with surface water such as rivers and soil, thus providing half of fresh water used on earth. This makes it hard to underestimate the economic and biosphere role of groundwater (Khublaryan,
2009).
As indicated by Behailu et.al (2017), the groundwater potential as well as the level of quality in urban centers and major cities is deteriorating as a result of urbanization, industrialization, population explosion and improper management of rainwater. The ground water quality is usually characterized by the chemical composition, physical characteristics and the biological parameters. The chemical composition of ground water evaluates the suitability of this water source for irrigation, animal and human consumption, industrial use among other purposes. It is notable that the chemical and physical parameters reflect inputs from activities like land use patterns, mining, acid
10 precipitation and industrial use among others. Therefore, there is the need to continuously monitor the quality of ground water in order to access the pollution levels, suitability for consumption by human beings and animals, the potential risk posed to the environment as well as sustainable management procedures for the groundwater (Behailu et.al, 2017).
In Africa, ground water plays a key role in ensuring sustainable provision of fresh water as most people lack access to piped water as a result of poor management of water resources and increased levels of urbanization. As noted by Nzeket et.al. (2019) in their study to assess the physicochemical and heavy metal properties of groundwater in Edéa region Cameroon, although the Cameroon has approximately 322 billion m3 thus making it the second country in Africa in terms of quantity of water resources, it is still unable to offer clean drinking water to its citizens. As a result of this, majority of the households in towns and villages have turned to using non-conventional sources of water supply like groundwater and streams among others (Nzeket et.al., 2019).
In Kenya, the occurrence and distribution of groundwater is controlled by the geology which is mainly the volcanic flows and intrusive rocks which is mainly found in the central and Rift valley. There also exist metamorphic terrains and sediment rocks in the coastal and eastern part of the country respectively (Owuor, 2019). In Nairobi Kenya, the situation is not any different. The water service provider in the city, Nairobi water and
Sewerage Company (NCWSC) is facing challenges to supply adequate quantities of water due to the ever-increasing population. In addition the government is unable to expand the water network in the upcoming urban areas to cater for the requirement of
11 potable water supply. Most places do not have pipelines and those who have their taps are ever dry. This has led to a wide use and dependency on groundwater sources such as shallow wells and boreholes (Gbadebo, et al., 2012). In Kawang’ware Nairobi, wells especially manual drilled wells have become a popular source that supplies drinking water to majority of people in the area. It is based on this study will look at the physicochemical properties of groundwater in the area in order to evaluate the suitability of consumption by both humans and animals.
2.2 Shallow Wells Pollution
Groundwater is a believed to be a reliable and safe source of water, because it is less prone to pollution since the soil acts as a barrier to pollutants which might get their way through into the water bearing rock. Unlike other forms of groundwater sources such as the deep wells (boreholes), shallow wells are more prone to contaminated (Adejuwon &
Mbuk , 2011). In a study done in Southern Malawi in 2009 by Pritchard et.al to determine the groundwater pollution in shallow wells, it was determined that majority of the physico-chemical properties of the water tested were within the recommended limits.
This study was similar to one carried out by Safdar, et al. (2013) whose findings assessment on drinking water quality and its impact on residents health in Bahawalpur
City established that the pH values of the water samples collected were above neutral (>
7), thus having an alkaline range. Further, the values of calcium (Ca) and sulfate (SO4) were above the permissible limits of 75 mg/l and 250 mg/l respectively, thus causing health related problems. However, for Pritchard et.al (2009) it was established that the water was grossly polluted with faecal matter, thus having high chances of
12 microorganisms which cause water borne related diseases. This is supported by another study carried out by Islam et.al (2016) to determine the safe distance between pit latrines and groundwater-based wells in the Ganges Atrai floodplains of Bangladesh. In this study, it was established that when the safe distance between the pit latrine and water point is not maintained, the chances of contamination increases significantly. However, this depends on aspects such as the hydrogeological conditions of a particular area and vertical and horizontal distances of the tubewell. For example in 2012, Ndambuki &
Kiptum (2012) found that by injecting bacteriophage in a pit latrine, it presence could be trace and detected in wells as far as 40 meters away within a span of one week. This was in their evaluation of contamination of well water by pit latrines in Langas, a periphery town of Eldoret town, Kenya in 2012.
In another study carried out in Abeokuta and Environs, Southwest, Nigeria to assess the pollution hazards of shallow well water, it was established that Fe, Pb, NO, EC, total coliform and bacteria count had mean values greater than WHO maximum permissible standards for drinking water. During the wet and dry seasons, the level of groundwater contamination was higher in the urban areas as compared to the peri-urban areas
(Oguntoke et.al, 2010). This is due to the fact that in the urban areas, ground water is more prone to contamination due to issues such as wrong placement of waste disposal facilities, increased presence of dumping sites and improper construction of the wells among other issues. However, it is important noting that contamination of water from shallow well not only results to microbiological contamination, but can also be a conduit of heavy metal contamination. In a study done by Luby (2008), it was observed that in
13 most parts of the South Asia region, shallow groundwater is contaminated with dangerously-high levels of arsenic. As a result of long-term exposure to the high levels of arsenic in the drinking water, the number of cases of cognitive impairment in children has been on the increase in this region. Although measures are being put by the respective governments to curb this issue, the pollution levels of water from shallow wells still continues to increase. This is attributable to increased industrial activities as majority of the economies in this region are rapidly developing such as China, South Korea and
Malaysia among others.
In another study carried out by the WHO in 2010, to assess the drinking water quality in the South-East Asia region, it was established that in the main sources of microbiological contaminations are from animal and human wastes. This is through various points like sewage disposal without any treatment, defecation at water sources, cross contamination from sewer lines, seepage from pit latrines and septic tanks as well as improper handling and storage of water at the home. For example, it is estimated that in this region, above
300 million people defecate in open spaces a factor which has led to increased cases of waterborne diseases as witnessed in 2009 in Nepal (WHO, 2010). The case is not different in Africa where ground water pollution, especially in the sub-Saharan Africa has been on the rise due to increased rate of urbanization, poor planning and changing climatic conditions among other notable factors. For example, in a study carried out by
Muraguri (2013) to assess the quality of groundwater in Nairobi County, Kenya, it was established that in all the thirty selected boreholes across the county, high levels of nickel and lead above the WHO (2008) standards were recorded in both dry and wet season. A
14 similar study carries out by Abila et.al (2012) established that there was bacteriological and chemical contamination of shallow wells in Kitui town, thus the water failed to meet the WHO guidelines for drinking water. The contamination was from latrines that were constructed near the shallow wells. It is notable that this situation replicates across most of the urban areas in Africa.
2.3 Physico-chemical properties of groundwater
The quality of groundwater in a given area can be observed through the physical and chemical properties possessed by the water. The physical parameters that determine water quality include temperature, turbidity, colour, taste, and odour of water. It is notable that the physical properties of groundwater should be determined in order to ascertain its suitability for daily utilization. As indicated by Peni & Listyani (2019), the chemistry of the groundwater can be seen from the Total Dissolved Solids (TDS), pH as well as the chemical composition. In regard to the chemical composition, the notable areas of consideration include the acidity and the hardness. The ion content of water is composed of metal ions, anions, and cations. In groundwater, the most important ions that include;
+ + 2+ 2+ 3+ 2+ 3+ 2+ Na ,K ,Ca , Mg , Al , Fe , Fe , Zn , NO3, NO2, SO42-, H2S, F, NH4, KMnO4, SiO2
Mn2+, and Cu2+ (Peni & Listyani, 2019).
It is notable that the degree to which ions on ground can impact on groundwater chemistry depends on the level of their concentration in the aquifer. Consequently, the quality of groundwater relies a great deal on the composition of water recharged into the ground, the reaction that happens in the aquifer, the interaction between the water and
15 media of the aquifer and the overlying soil (Adekunle, et al., 2007). There are various human activities that have an impact of the levels of the physico-chemical and biological properties of ground water. Human activities such as industrial waste effluents, sewerage disposal and agriculture can by far and large alter the quality and fitness of ground water for human use and consumption (Adekunle, et al., 2007). Local and international standards determine the groundwater quality depending on the composition of these parameters. Some of the standards include: Guidelines for Drinking (WHO, 2008),
Kenya Bureau of standards (KEBS) (Mbura, 2018).
2.3.1 Turbidity
Turbidity is the level at which the water clarity is reduced due to the presence of suspended matter scattering or absorbing down dwelling light. Water is regarded as turbid at the time when the suspended particles are conspicuous. Suspended matter, such as organic matter, microscopic organisms, clay and silt particles, and colloids makes the natural water to be turbid. Suspensions or tripton, inorganic suspended materials, form adsorption and desorption surfaces all have the ability to aggregate with the substances that are dissolved, algae and bacteria. The substances that are absorbed are available for the zooplankton, bacteria and algae in rivers and other water bodies. Turbidity is measured in nephelometric turbidity units (NTU). It is notable that turbidity has an effect to color of the water as well as promotes microbial proliferation, thus having a negative effect to the quality of water. As indicated by Oluyemi et al., (2014), during the wet seasons, there is a high level of turbidity and low turbidity during the dry season. This is due to the fact that during the dry season, high amount of silt and other materials are
16 deposited into aquifers. As per the World Health Organization and KEBS drinking water should not have a turbidity of more than 5 NTU and should ideally be below 1 NTU
(Oluyemi et al,. 2014).
2.3.2 Total dissolved solid
The total dissolved solids (TDS) is a term used in describing the small amounts of organic matter and inorganic salts present in solution in water, calcium, carbonate, sulfate hydrogen carbonate, chloride magnesium, sodium, and potassium cations and nitrate anions are usually the principal constituents. When there is the presence of dissolved solids in water, the taste is affected. In relation to the TDS levels, the taste of water varies significantly as follows: excellent when it is less than 300 mg/litre, good when it is between 300 and 600 mg/litre fair when it is between 600 and 900 mg/litre, poor when it is between 900 and 1200 mg/litre, and unacceptable when it is greater than 1200 mg/litre
(1). It is notable that from natural sources, concentrations of TDS varies from less than
30mg/litre to as much as 6000 mg/litre (World Health Organization, 2003). This depends on the solubility of minerals that are found from various geological regions. It is notable that surface sun-off leads to increased level of TDS by increasing elements such as chlorides, nitrate, sodium, bicarbonates, potassium, calcium and magnesium (Oluyemi et al,. 2014).
2.3.3 pH pH is the measure of the hydrogen potentiality in water and the term is used to express the intensity of alkalinity or acidity of a given solution (Mbura, 2018). In Water, pH is
17 measures the acid-base equilibrium. In most natural water, pH is controlled by the carbon dioxide –bicarbonate-carbonate equilibrium system. Based on this, when there is an increase in the amount carbon dioxide, the pH level is reduced and the vice-versa. It is also notable that temperature alters the pH levels in that in pure water, increase in temperature by 25oC decreases the pH level by 0.45. However, this effect of the temperature on pH is modified in water with a buffering capacity imparted by hydroxyl ions, carbonate and bicarbonate. For drinking water, the acceptable pH lies within a range of 6.5-8.5. However, for natural waters, the level of pH varies significantly as a result of issues such acidic rainfall and high pH in limestone areas (World Health Organization,
2007).
2.3.4 Temperature
The temperature not only helps in determining the biological, chemical, and physical properties of water, but also the possible health effects. As noted by Government of
Canada. (2009), the temperature in water governs the type of aquatic life living in it as well as regulates the total amount of oxygen concentration that can be absorbed in the water. Further, temperature influences the biological and chemical reaction as well as the sensitivity of organisms to pollution. According to the WHO and KEBS, the permissible temperature limit is between 28 and 32oC. It is notable that when there is the presence of effluent contamination level of temperature is increased (Murhekar, 2011).
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2.3.5 The electrical conductivity
Pure water is a poor conductor of electricity thus acting as an insulator. However, increase in the level of ion concentration enhances the conductivity of water, therefore, the amount of dissolved solids in water are the ones which determines the EC levels. The other factor that affects the EC levels is the temperature where increase in temperature raises the EC and the vice-versa. According to WHO standards, the acceptable values of
EC should not exceeded 400 μS/cm (Meride& Ayenew, 2016).
2.3.6 Total hardness
Water hardness is the method that is traditionally used to measure water capacity to react with soap, where soft water requires very less amount of water to produce the required lather. The issue of hardness is not contributed by a single substance but rather a ray of polyvalent metallic ions that are dissolved. The most predominant one are magnesium and calcium cations. However, other cations such as manganese, strontium, barium, iron, and zinc also significantly contribute to the total hardness. The general expression of hardness is milligrams of calcium carbonate equivalent per litre. In this regard, soft water is water having less than 60 mg of milligrams of calcium carbonate per litre. Dissolved polyvalent metallic ions from seepage, run-off soil, and sedimentary rocks are the natural sources of water hardness (World Health Organization, 2007). As per the KEBS guidelines (2010), the total hardness is 500mg/l (Mbura, 2018).
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2.3.7 Sulphates ions
Sulfates are naturally occurring in minerals such as barite (BaSO4), gypsum
(CaSO4·2H2O) and epsomite (MgSO4·7H2O), and the above dissolved minerals plays a key role in the overall mineral content in water. According to WHO (2004), for drinking water, the reported taste median threshold are 350 mg/litre for sodium sulfate, 525 mg/litre for calcium sulfate and magnesium sulfate. However, in drinking water, the optimal taste for calcium and magnesium sulfate is 270 and 90 mg/litre respectively. As per WHO and KEBS, the maximum suggested level of sulfate is 500 mg/l (WHO, 2004).
2.3.8 Nitrates ions
Nitrate is mainly used in inorganic fertilizers. Also, it used in the production of explosives and acts as an oxidizing agent. Further, sodium nitrate is used in preservation of food such as cured meats and purified potassium nitrate is used in the production of glass. In other cases, nitrate is added to food and serves as a nitrite reservoir. There is a possibility that nitrate can reach the groundwater and surface water due to agricultural activities such as the use of manure and inorganic nitrogenous fertilizers. Nitrate can also reach the ground water and surface water through oxidation of nitrogenous waste materials from animal and human excreta such as the septic tanks. In industrial areas, concentrations of nitrate of about 5mg/l in rainwater have been witnessed (World Health
Organization, 2011). In water, the permissible limit of nitrate is 10 mg/l (KEBS, 2010).
Above this permissible level, they can result to oral and gastrointestinal diseases.
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2.2.9 Phosphate ions
Phosphorus is one of the key elements crucial for the growth of animals and plants.
Phosphates get into the waterways from laundry, cleaning, phosphorus rich bedrock, industrial effluents, animal and human waste as well as fertilizer runoff. When they over fertilize the aquatic animals, they have detrimental effects resulting into stepped up eutrophication. The natural levels of phosphate range between 0.005 and 0.05 mg/L.
According to WHO, the permissible levels of phosphates should be 0.02 mg/l (20 μg/l)
(KEBS, 2010).
2.3.10 Lead ions
Lead is one of the most found heavy elements and accounts for 13mg/kg of the earth’s crust. In nature, there are notable isotopes of lead which exists, which includes 208Pb,
206Pb, 207Pb and 204Pb in their order of abundance (World Health Organization, 2011).
Lead is used in the production of cable sheathing, ammunition, glazes, pigments, lead acid batteries, solder, rust inhibitors, plastic stabilizers, and alloys. Lead pipes have been used in plumbing and other distribution systems though this has been phased out in most countries across the world. Consumption of lead even in small proportions is harmful to humans since the metal is a cumulative general poison. Lead affects the central nervous system as well as causes various types of cancer (Murhekar, 2011). For lead, the permissible level in drinking water is 15 µg/L (KEBS, 2010).
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2.3.11 Iron ions
In terms of abundance, iron accounts for 5% of the earth’s crust and comes second after aluminum. Elemental iron is not easily found in nature as Fe3+ and Fe2+ combines readily with sulfur- and oxygen- containing compounds. This leads to the formation of carbonates, sulfide, oxides and hydroxides. In nature, iron is mostly found in oxide form.
Groundwater contains iron (II) whose concentration can range between 0.05 and 0.1 mg/litre. However, this does not affect the turbidity or the color of the water when pumped from the well. Within distribution systems and waterworks, iron leads to undesirable growth of bacteria leading to deposition of coating on the pipes. The permissible level of iron in drinking water is 10 milligrams per liter (mg/L) (KEBS,
2010).
2.3.12 Cadmium ions
Cadmium is a heavy metal that is usually used as an anticorrosive as well as used in electroplating steel. Cadmium compounds are used in nuclear reactors, electric components and in electric batteries. In unpolluted natural water, the concentration of cadmium is usually less than 1 μg/l. Contamination of drinking water may occur due to the presence of cadmium in cadmium-containing solders in fittings or when cadmium is an impurity in the zinc of pipes that are galvanized. As indicated by Alloway (2012), the level of cadmium tends to be higher in those areas that are supplied with soft water having low pH levels. Therefore, this tends to be more corrosive in those plumbing systems containing cadmium. The maximum permissible level of cadmium in water is
0.005 milligrams per liter (mg/L) (Alloway, 2012).
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2.3.13 Zinc ions
Zinc ions can be traced in small amounts in almost all igneous rocks and when in drinking water, zinc produces an undesirable taste. The metal is used in the production of alloys as well as galvanizing iron and steel. Zinc oxide, used as white pigment in rubber is the most used compound of zinc. In natural surface water, the level of concentration of zinc is usually 10 μg/litre and between 10 and 40 μg/litre in groundwater. The permissible level of zinc in water is 5 mg/L (World Health Organization, 2003).
2.3.14 Sodium ions
Sodium ions are important in the growth of human hence the occurrence of sodium ions in water at lower levels has no health implications. According to KEBS (2010) guidelines, in water, the permissible level of sodium is 200mg/l. However, above this limit, it can result to kidney failure and hypertension.
2.3.15 Potassium ions
Potassium ions are essential for humans and are rarely found in drinking water at levels which pose danger to the health of humans. Potassium can take place in drinking water when potassium permanganate is used as an oxidant in water treatment. The permissible level of potassium is 50mg/l above which it can lead to kidney failure (Mbura, 2018).
2.4 Indicator micro-organisms
The presence of these organisms in water is suspect of fecal contamination and hence the presence of other pathogenic bacteria and thus a health risk (Rajendran, et al., 2006).
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Indicator bacteria have been widely used as a standard procedure to evaluate the sanitary conditions of drinking water. These include coliform bacteria and fecal bacteria specifically, E.coli (USEPA, 2001). These contaminants from the surrounding get to the underground water through leaching down the soil profile (Howard , et al., 2002).
Presence of bacteria in water indicates the preference of pathogenic organisms causing water related diseases (Nassinyama, et al., 2000). Commonly referred to microorganism indicators include total coliforms and the faecal coliforms which are mostly associated faecal contamination.
2.4.1 Total coliform bacteria (TC)
Most of the coliform group bacteria generally found in the environment are usually harmless (USEPA, 2006). Total coliforms are used in routine monitoring of drinking water supplies after the conventional treated (WHO & UNICEF, 2000). The presence of total coliforms in water samples indicates the inefficiency of the disinfection process and thus possibility of the presence of other pathogenic opportunistic bacteria such as
Salmonella spp, Shigella spp, V. cholerae, and pathogenic E. coli (Payment, et al., 2003).
Ideally, no total coliform should be present in drinking water according to WHO.
2.4.2 Faecal coliform bacteria (FC)
Faecal coliform are a sub set of total coliform group. They are Gram negative bacteria also known as thermotolerant coliforms since they are able to survive and ferment lactose at high temperatures of 44.5º C.They are usually present in large numbers in the intestinal tract of human and animals. Among these groups of coliforms, there exists those that
24 originate from non-feacal sources such as Klebsiella spp, Enterobacter spp. and
Citrobacter spp. While E. coli is specifically from faecal origin. The presence of these organisms in water shows that the water is contaminated with feces or sewage and therefore the potential presence of pathogenic bacteria (USEPA, 2006). Elimination of these bacteria from water is used to determine the efficiency of water treatment system.
No sample should contain Fecal coliform or E. coli (WHO 2012).
2.5 Water quality and Sanitation in relation to waterborne diseases
Most coliforms in water are harmless but the presences of certain type of bacteria like fecal coliforms or E.coli is a signal of presences of feces or sewage waste in water. It is the presence of this feces and sewage waste that usually harbor disease causing pathogens. Ingestion of such pathogens via water results to transition of waterborne diseases which are a major cause of death and illness in the worldwide (UNICEF, 2008).
An outbreak of these diseases is mostly linked to lack of potable water in most parts of the developing countries. Diseases like diarrhoea are largely caused by unsafe water, inadequate sanitation and poor hygiene both at personal level and community levels especially where a common water sources is used among human population (UNICEF,
2008).
The diseases affect all age groups i.e. children under-five years, over five and adults are not spared either (USAID, 2005). Municipal water supplies in developing countries are often insufficient and therefore shallow wells provide the communities with the most convenient option. Most of these sources are unprotected and are susceptible to external
25 contamination (WHO & UNICEF, 2000). The waterborne infections tend to spread very fast in an area were the people share a common source of water. These infections if not controlled may result in an epidemic thereby affecting a very large number of the community. The severity may depend on a number of factors like the age, health and immunity of the individual (Potgieter , 2007). The most vulnerable class of people to suffer the effect of water borne diseases include infants, children under five, those with compromised immunity and living under unsanitary conditions(WHO & UNICEF,
2000).Some of the water borne diseases are discussed below;
2.5.1 Diarrheal Disease
This disease is characterized by stools of decreased consistency and increased number of times in a day. The victim may become dehydrated due to loss of body fluids. In developing countries, rotavirus is often responsible for diarrheal diseases and many death especially in children under the age of five (Rogers, et al., 2002). Approximately 88% of these deaths are attributable to unsafe water supply, inadequate sanitation, and poor hygiene (Unicef/WHO, 2008). The introduction and promotion of oral rehydration therapy (ORT) has reduced the severity of the disease symptoms in victims (Bern, et al.,
2003.). The diarrhoeal disease are transmitted through the ingestion of theses bacteria via the mouth (Farr, et al., 2001).
2.5.2 Cholera
Cholera is caused by a bacterium Vibrio cholerae (V. cholerae).Infection is usually contracted by ingestion of water or food contaminated by infected human faecal material.
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It can also be spread by personal contact with infected persons. Its incubation period is usually between 1 to 3 days (CDC, 2014). The infection may be mild or severe characterized by profuse watery diarrhea, and vomiting. In most cases the affected persons may be dehydration due to loss of fluids from the body (CDC, 2014). With delayed treatment, it may result to death within hours although with suitable treatment death may be averted (Wallace, 2008; Gray , 2008). Cholera outbreaks are still a challenge in countries with unsafe water supplies and inadequate hygiene (Cabral, 2010;
WHO, 2003).
2.5.3 Bacillary dysentery (Shigellosis)
This disease is caused by bacteria of the genus Shigella –Shigella dysenteriae. The disease is characterized by the presence of blood in liquid stools (Bern, et al., 2003.).
Incubation period ranges from less than 12 hours to 6 days depending on various factors like the concentration of bacteria ingested and the age of the individual. The infection manifests with abdominal pain followed by mucous diarrhoea with some blood stains
(Cabral, 2010; Wallace, 2008).Good sanitation and hand washing practices have proven to be effective in the control of the spread of this disease (WaterAid, 2013).
2.5.4 Typhoid fever
Typhoid fever is caused by Salmonella typhi bacteria. It is usually contracted by ingestion of contaminated food or water. The water or foods are contaminated through stool containing a high concentration of these bacteria, by people who have had an acute illness. Once the water supply which is commonly used by the community is
27 contaminated, it spreads in the area affecting many people. New outbreaks may be experienced through people who previously suffered a mild attack that went unrecognized but they become carriers for many years without showing symptoms
(UNICEF, 2008).
2.6 Gaps Identified in literature
While many studies have been done to access the quality of ground water in Nairobi, majority of the studies have focused on the physico-chemical properties leaving behind the microbiological characteristics. For example, Muraguri, P. (2013) studied the physico-chemical properties of thirty selected boreholes distributed in various divisions of Nairobi during the wet and dry seasons. Although the findings forms important basis to the policy makers, there was the need to carry out microbiological properties to ascertain the extent to which the water taken by the residents of Nairobi may be leading to the increased cases of waterborne diseases. Further, majority of the studies have not paid attention to contamination levels in water obtained from shallow wells as majority concentrates in water obtained from the boreholes. Therefore, this study will focus on the level of shallow well contamination in Kawangware, one of the urban slum areas found in Nairobi.
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CHAPTER THREE: RESEARCH METHODOLOGY
3.1 Overview
The study analyzed the physico-chemical and microbiological quality of groundwater used by the people of Kawangware. The fieldwork was carried in the month of July and
August 2017 and involved collection of data from the field and sampling for laboratory analysis.
3.2 General information of the study area
The study was undertaken in Kawangware location of Nairobi County in Kenya.
Kawangware lies between 1°16'60" S and 36°43'60" E. It is located approximately 15 km from Nairobi Central Business District (NCBD). It is adjacent to the rich agricultural county of Kiambu. It is sandwiched between Lavington and Kangemi. As per 2013, the population of the three study areas Kawangware, Gatina and Kibiro sublocation was
33,707, 43,627 and 33,707 respectively, and covers an area of 1.2, 1.5 and 1.2 square kilometers respectively. In a study done by Matata (2004), it was established that, each household in Kawangare has 3 children with 7 maximum constituting around 50% of the population. Also, out of the 147 interviewed households, 61% of the respondents were married implying that the area has a high dependency rate on an income of around
Ksh5000 per household per month. In terms of education per household, it was established that 50% of the household heads had secondary education levels and 80% of the residents depends on the informal sector for employment (Matata, 2004). The area is flat and having slight slopes in northeast heading to the east direction, and the Nairobi
River follows that direction. The only natural drainage in the areas is the Nairobi River, a
29 factor which forces the runoff to stagnate waiting for percolation into the soil due to the nature of the soil in the area. The soil is almost black cotton soil with a smaller coefficient of permeability and higher porosity. Therefore, it takes notable amount of time before the runoff water to percolate to the ground (Matata, 2004). The Kawangware area has a character of rural setting, though the subsistence-farming areas have given way to housing pattern. Majority of the landowners have freehold interests on land, a factor which has enabled them to construct rental houses for monetary gains through rent. As a result of increased population in the area, the demand for accommodation has significantly increased in the recent past. However, despite the efforts made by the government in terms of housing provision, it is clear that little or nothing has been done to improve the situation of low-income residents. This has given a leeway for many of the house owners to exploit the residents as the rent is not controlled (Matata, 2004). The area has good communication infrastructure such as roads hence suitable for human settlement. Due to these factors the population of Kawangware surged into an informal settlement characterized by shanties houses and high human presence, like other informal settlements in Nairobi and its peripheries, the area is poorly serviced by piped water and as a result residents relying heavily on groundwater as the reliable source of water for domestic use. Groundwater mainly from shallow wells is readily available and always seen as the cheaper option of water for consumption. The area has a poor garbage collection, running sewage, use pit latrines and septic tanks for human waste disposal, indiscriminate construction of wells, limited coverage in city council piped water supply.
Water samples were drawn from three sub-locations namely: Kabiro, Gatina and
Kawangware sub location as shown on the figure below.
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Map of Kenya
Nairobi County
Figure 3.1: Map of Kawangware location showing sampling sites. Source: Author, 2019
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3.3 The Design of the Study
Cross-sectional Survey research design was employed in the study to assess the level of physico-chemical and biological parameters of well water in the study area. Sample units were purposively selected.
3.4 Sampling and Sampling procedure
3.4.1 Sample Selection and Sample Size.
The study area is not homogeneous hence was clusted in three sub-location namely
Kabiro, Gatina and Kawangware.
The sample size was determined using Yamane’s simplified method of determining sample size i.e. n=N/ {1+N (e) 2} (Polonia, 2013)
Where: n = Sample Size e = Error Limit (0.1)
N= Population Size
The wells were sampled as follows amongst three sub-locations namely Kabiro, Gatina and Kawangware 7, 13, 8 wells respectively giving a total of 28 wells. All the wells were purposively selected. Samples were collected in the month of July 2017 and the same was repeated in the month of August 2017.The Samples were collected twice a day, in the morning hours between 6.00 am-9.00am and evening 3.00pm-5.00pm when the residents were fetching water. A total sample of 112 was collected.
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3.4.2 Sampling procedure
A volume of one liter water samples for physico-chemical analysis from the shallow wells were collected in clean plastic bottles .In-situ measurements of temperature, pH,
Electrical conductivity (EC) and TDS were carried out in the field at the point of sampling. Samples for analysis of Zn, Pb, Fe and Cd were preserved with 2 ml concentrated nitric acid. There after the samples were packed in cool boxes and transported to the laboratory for further analysis. Turbid samples for laboratory analysis were filtered using a 0.45 μm pore diameter filter papers before analysis. All samples were stored refrigeration conditions at 40 C.
Water samples for microbiological analysis were collected in glass bottles. The bottles had been washed and sterilized at 121° C prior to sampling. The water sample bottles were labeled with the name of the site, date and time of sampling. They were carried in a cool box and transported to the laboratory under refrigeration condition within 6 hours for analysis. Samples not analyzed on the same day were stored in the refrigerator at 40 C for not more than 24 hours.
3.5 Physico-chemical Analysis
The parameters tested were temperature, PH, electrical conductivity, total dissolved solids, turbidity, total hardness, sodium, potassium, nitrates, phosphate, sulphates, Zn, Pb,
Fe, Cd total coliforms and feacal coliforms.
The parameters were tested in accordance with the Standard methods for the Examination of water and waste waters (APHA, 2005) and the results obtained were compared with
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KEBS drinking water guideline in order to determine the quality of water and hence the suitability of the groundwater used in Kawangware. Selected parameters were analyzed for each sample collected. All the equipments were calibrated and distilled water used throughout the analysis.
3.5.1 In-situ measurements
The physical parameters that were carried out in the field included; measurements of temperature, electrical conductivity, total dissolved solids, pH and turbidity were taken in accordance to (APHA, 2005).
3.5.1.1 Temperature
A simple mercury thermometer was used to take the temperature of each of the water samples and the results recorded in degrees centigrade. The temperature was taken by dipping the thermometer inside a beaker containing the water sample. The readings were noted after they stabilized.
3.5.1.2 Conductivity and total dissolved solids
A field multi parameter conductivity/TDS meter type Hanna HI 99300 was used to determine water conductivity and TDS on site. The meter electrode rinsed with distilled water was dipped in the sample and the value recorded in μS/cm. The meter had been prior calibrated with potassium chloride solution (KCl 0.01N).
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3.5.1.3 pH
The pH was determined by potentiometric method using pH meter Hanna HI model
99121. A two point calibration of the pH probe was performed using pH buffer 4 and pH buffer 7. For sample pH determination, the probe was dipped into a 50 ml of sample and the readings recorded when the reading stabilized.
3.5.1.4 Turbidity
Turbidimeter was used in the determination of Turbidity. A Jenway- 6035 Portable
Turbidimeter was used after calibration according to the manufacturer’s instructions.
Distilled water was used to zero the equipment thereafter two standards 100 NTU and 40
NTU were used to calibrate. A volume of 10 ml of sample was taken after thorough shaken and transferred into a cuvette and readings taken in Nephelometric units.
3.5.2 Laboratory analysis for chemical analysis
The rest of the parameters were analyzed in the Kenyatta University Environmental
Science laboratory where; Ultraviolet-visible spectrophotometer model Jenway 6300 was used to analyze phosphate, nitrates and sulphates, flame photometer model
Sherwood 410 was used to analyze sodium and potassium, volumetric titration against
EDTA was used for total hardness (APHA, 2005).
3.5.2.1 Total hardness
EDTA titrimetric method was used to determine the total hardness. Total hardness buffer
(NH4Cl-NH4OH) and black tea indicator were used alongside 0.01N EDTA solution as
35 the titrant. The titre reading was taken after a pink end point was achieved. Samples with high conductivity were diluted by a factor. The Concentrations were calculation as below;
Total Hardness = (Titre x 20 x D.F.)
3.5.2.2 Nitrates
- Concentration of nitrates (NO3 ) was determined by spectrophotometric screening method
Using UV Vis spectrophotometer Jenway 6300. Standards of various concentrations ranging from 0.2 to 1.5 mg/l were prepared. About 1 ml of 0.1N HCl was added into each. Absorbance of standards was read at two wavelengths (at 220 nm and 275 nm). A standard curve was then obtained from the standards from which the sample concentrations were extrapolated. Samples were treated the same way as the standards before obtaining their absorbance.
3.5.2.3 Determination of potassium (K) and sodium (Na)
Flame photometric estimation of K and Na ions was done. Respective standards solutions were made from potassium chloride and Sodium chloride. Concentrations of the ions were then determined directly reading at wavelength of 766.5 nm for potassium and 589 nm for sodium ions. Samples with high concentrations which was indicated by high conductivity, were diluted to a factor. The equipment was standardized using two standards; (2 mg/l and 10mg/l) and 1 ml of sample analyzed.
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3.5.2.4 Phosphates
Phosphate was analyzed by use of ascorbic acid followed by readings on a UV vis spectrophotometer. About 50 ml aliquot of the sample was measured in a 50 ml conical flask. About 8 ml of combined reagent prepared according to manufacturers’ specification consisting of ascorbic acid, ammonium molybdate, potassium antimonyltartarate and sulphuric acid was added. The tube was shaken well and left to stand for 10-30 minutes to develop a stable blue colour thereafter reading was taken at
880 nm absorbance using spectrophotometer.
3.5.3 Total metal determination using atomic absorption spectrophotometer (AAS)
Working standards for calibrating Atomic Absorption Spectrophotometer (AAS) equipment were prepared serially by diluting the stock solutions (1000 ppm) using the formula C1V1=C2V2, where C1 was the concentration of the stock solution, C2 was the required concentration of the standard, V1 was the volume of the stock solution taken for dilution and V2 was the volume of the standard prepared from the stock solution.
3.5.3.1 Digestion of samples for Zn, Pb, Fe and Cd
In this analysis, 5 ml of concentrated nitric acid was added to 50 ml of sample of water in a 100 ml beaker. This mixture was heated on a hotplate to boil to a volume of 25 ml. It was then transferred into 100 ml volumetric flask and distill water was added to fill up to the mark where it was filtered and transferred into the pre-cleaned sample bottle and taken for further analysis. A blank solution was similarly prepared. The absorbance of the blank was taken before all the analysis.
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3.5.3.2 Determination of metals
The levels of Cd, Zn, Pb and Fe were determined with the Atomic Absorption
Spectrophotometer. The principle behind the AAS is that atoms are capable of absorbing energy at a specific wavelength when passed through a solution containing those specific atoms. The flame used for the analysis was air-acetylene mixture. A blank analysis was performed with distilled water treated just as the sample. The respective wavelengths employed for the metal determinations were Fe at 248.7 nm, Pb at 217.0 nm, Zn at 213.9 nm and Cd at 228.8 nm.
3.5.4 Microbiological Analysis
Multiple tubes fermentation techniques (APHA, 2005) for determination of coliforms in water samples was adopted. The number or the population given as most probable number (MPN) of coliforms in the water sample was estimated by the number of positive tubes corresponding with standard MPN statistical table and recorded as MPN/100 ml.
This method is a three step method involving a presumptive test, followed by a confirmatory test and finally a complete test as described below;
3.5.4.1 Determination of Total coliforms and Feacal coliforms
The standard total coliform fermentation technique was used to determine the numbers of fecal coliforms in the samples. The method is a three step technique that involves use of multiple tubes for the fermentation process. Serial dilutions of 10-1 to 10-2 were prepared by taking 1ml of the sample into 9 ml of sterile distilled water.
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Presumptive coliform test was performed using Lactose fermentation broth prepared according to manufacturer’s instructions. Three sets of tubes were inoculated with 10 ml,
1ml and 0.1ml of water samples. Each set contained five tubes. The tubes were incubated at 370 C ± 0.5 for 24 to hours and examined for acid and gas production. Acid production was determined by colour change of the broth from reddish purple to yellow and gas production confirmed by gas entrapment in the Durham tube which was an indication of presence of coliform bacteria in the sample. Confirmed test was performed by transferring a loop of culture from a positive tube into a tube of Brilliant Green Lactose
Bile (BGLB) with Durham tubes. The tubes were incubated at 370 C for 24 to 48 hours for total coliform and 440 C for faecal coliform and observed for gas production.
Tubes showing colour change from purple to yellow and gas collected in the Durham tubes after 24 hours were identified as positive for feacal coliforms. Counts per 100ml were calculated from MPN tables.
3.6 Data Analysis
The data obtained from the analyzed physico-chemical and microbiological parameters was displayed on tables and graphically using excel and compared KEBS (local standards) to check if they fall within acceptable limits. The collected data was captured in STATA-14 software which generated means and standard deviation to help in answering research objectives. The formulated hypotheses were tested using the students t- test at 95% confidence interval.
39
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Introduction
The chapter presents the findings of the analyzed parameters of the shallow well water.
The concentration for each parameter was compared with KEBS (2010) drinking water standards so as to determine the quality of the sampled water. The findings of the research have been presented in form of tables and graphs and their discussions clearly given as below.
4.2 Physico-chemical parameters of groundwater used by household in Kawangware
The minimum, maximum and mean values of the physico-chemical properties of groundwater in Kawangware location are shown in Table 4.1 to Table 4.3 respectively.
Table 4.1: Physico-chemical parameters of groundwater for Kabiro site
Parameters units Mean KEBS Std. Dev Range p-value (2010) Min. Max. Temperature °C 23.5 - 2.02 20.9 26.4 - pH 8.1 6.5-8.5 0.24 7.8 8.69 0.002 Conductivity as μS/cm 310.7 2500 24.46 270.5 350.0 0.001 EC TDS mg/l 195.6 1500 15.91 167.7 217.0 0.001 Turbidity NTU 16.0 5 35.77 0.0 100.9 0.149 Hardness as mg/l 13.8 500 5.49 9.41 27.0 0.001 CaCo3 Sulphate as mg/l 0.1 450 0.26 0.01 1.0 0.001 SO4 Nitrate as No3 mg/l 17.9 10 1.66 14.3 20.1 0.001 Phosphate as mg/l 6.1 2.2 5.91 0.04 14.0 0.084 PO4 Lead asPb mg/l 0.2 0.01 0.34 0.06 1.0 0.001 Iron as Fe mg/l 0.1 0.3 0.04 0.03 0.17 0.001 Cadmium as mg/l 0.04 0.003 0.007 0.03 0.06 0.001 Cd Zinc as Zn mg/l 0.1 5 0.10 0.001 0.3 0.001 Sodium as Na mg/l 73.3 200 3.77 65.8 80.0 0.001 Potassium as K mg/l 7.9 50 1.08 6.0 10.0 0.001
40
In Kabiro site, all other parameters were within the acceptable limits for drinking water according to KEBS standards except for turbidity, nitrates and phosphates which were much beyond the KEBS standards. Cadmium was also evident in the water from this site as seen in table 4.2.
Table 4.2: Physico-chemical parameters of ground for Kawangware site
Parameters Units Mean KEBS Std. Dev. Range p- (2010) Value Min. Max. Temperature °C 22.0 - 2.72 19.5 28.8 pH 7.8 6.5-8.5 0.33 7.21 8.34 0.000 1593. Conductivity( EC) μS/cm 966.3 2500 540.18 118.2 0.000 1 Total dissolved solids mg/l 603.1 1500 336.47 73.82 987.7 0.000
Turbidity NTU 12.0 5 14.84 0.0 50.1 0.066 345.2 Hardness as CaCo mg/l 164.8 500 106.94 8.9 0.000 3 6
Sulphate (SO4) mg/l 0.44 450 0.52 0.03 1.12 0.000
Nitrate ( NO3) mg/l 18.4 10 0.51 17.5 19.7 0.000
Phosphate( PO4) mg/l 9.5 2.2 13.87 0.02 42.8 0.234
Lead as Pb mg/l 0.08 0.01 0.01 0.06 0.09 0.000
Iron as Fe mg/l 0.18 0.3 0.07 0.01 0.3 0.001
Cadmium(Cd) mg/l 0.04 0.003 0.01 0.03 0.05 0.000
Zinc (Zn) mg/l 0.02 5 0.01 0.01 0.03 0.000
Sodium ( Na) mg/l 113.3 200 26.24 74.5 154 0.000
Potassium (K) mg/l 39.8 50 32.02 6.0 116 0.134
41
Water from Kawangware site was characterised by high levels of turbidity, nitrates and phosphates in addition to exhibiting substantial levels of heavy metals like lead and cadmium beyond the maximum limits as desired by KEBS as seen in table 4.3.
Table 4.3: Physico-chemical parameters of ground for Gatina site
Parameters Units Mean KEBS Std. Dev. Range p-value (2010)
Min. Max.
Temperature °C 21.76 - 3.08 17.5 30.1 PH 8.4 6.5-8.5 0.85 7.2 9.88 0.7501 Conductivity as EC μS/cm 601.3 2500 322.3 117 1254. 0.000 6 Total dissolved solids mg/l 401.1 1500 200.79 121.7 777.9 0.000 Turbidity NTU 32.8 5 25.33 0.6 78 0.000
Hardness as CaCo3 mg/l 107.6 500 0.13 11.9 234 0.000
Sulphate as SO4 mg/l 0.375 450 0.44 0.01 1.5 0.000
Nitrate as NO3 mg/l 18.5 10 0.68 17 19.8 0.000
Phosphate as PO4 mg/l 6.7 2.2 5.28 0.02 15.8 0.001 Lead asPb mg/l 0.19 0.01 0.30 0.05 1 0.000 Iron as Fe mg/l 0.3 0.3 0.30 0.07 1 0.058 Cadmium as Cd mg/l 0.04 0.003 0.01 0.03 0.06 0.000 Zinc as Zn mg/l 0.2 5.0 0.34 0.01 1.2 0.000 Sodium as Na mg/l 97.0 200 23.51 68.7 142.2 0.000 Potassium as K mg/l 25.5 50 17.47 7.5 55 0.000
In Gatina site, all other parameters were within the acceptable limits for drinking water according to KEBS standards except for turbidity, nitrates and phosphates which were much beyond the permissible levels according to KEBS standards. Cadmium and lead were also evident in the water from this site as seen in table 4.3.
42
4.2.1 Temperature
The mean temperature for the water samples in the study area ranged from 21.76º C to
23.5º C with Kabiro recording the highest temperature of 23.5º C and the lowest temperature of 21.76º C recorded at Gatina as seen in figure 4.1.
Figure 4.1: Mean temperatures of the shallow well water in Kawangware location
It is notable that the relatively low temperatures are due to the general cool weather that prevailed during the sampling times; in the morning and evening. Water temperature plays an important role by influencing the chemical and bio-chemical characteristics of water. High temperature decreases the solubility of different gases especially carbon dioxide and other volatile gases which impart taste in the water (Karunakaran, et al.,
2009). However, temperature of a water body is affected by a number of factors such as climate and the effect of direct sunlight and depth of the water (Ekhaise and Anyansi,
2005).
43
4.2.2 pH
The mean pH for the entire study area ranged from 7.8 to 8.4 with the highest of 8.4 being recorded at Gatina and the lowest value of 7.8 at Kawangware with Kabiro recoding a pH value of 8.1 (Figure 4.2). The pH for all the samples in the area were slightly basic hence making the water toxic (Safdar et.al, 2013). There was a significant difference (p ≤ 0.05) between pH of Kabiro and Kawangware sites and those of KEBS
(Table 4.1 and 4.2). While there was no significance difference (p ≤ 0.7501) between the pH of Gatina and KEBS (Table 4.3) however, the pH of the water in the area was within the acceptable standards in accordance to KEBS as per the figure 4.2.
Figure 4.2: Mean pH levels of the shallow well water in Kawangware location
Temperatures bring about changes in the pH of water by bringing about changes in the physico-chemical condition of the water (Trivedi, et al., 2009). The cool temperature water did not favour the chemical activities in water which could have resulted to either decrease or increase in pH. Similar trends were experienced by (Basavaraja , et al., 2011) in their study on the quality of water in India.
44
4.2.3 Electrical conductivity
Mean conductivity of water samples ranged between 310.7 μS/cm and 966.3 μS/cm with the lowest being recorded at Kabiro and highest at Kawangware (Table 4.2 and
4.3).Gatina sub-location recorded a value of 601.3μS/cm, although these values fell within the KEBS acceptable limits of 2500μS/cm as per figure 4.3)
Figure 4.3: Mean Electrical conductivity of the shallow well water in Kawangware location
From the figure 4.3, it is important to note that, there was a significant difference (p ≤
0.05) between the mean conductivity values for all the sites and that of KEBS (Table 4.1,
4.2 and 4.3). The Electrical conductivity of the water in this area was much lower as compared to that of KEBS. Similar trends in electrical conductivity have been observed in studies by (Adejuwon & Mbuk , 2011) on the biological and physiochemical properties of shallow wells in Ikorodu town of Nigeria. This means that the water in the study is a poor conductor of electric current as it is not ionized (Basavaraja et al., 2011).
45
4.2.4 Turbidity
Turbidity of the well water samples varied from 12.0 to 32.8 NTU with the lowest recorded at Kawangware and the highest at Gatina (Table 4.1,4.2 and 4.3) Kabiro sites recorded a mean turbidity value of 16.0 NTU. These values exceeded the KEBS recommended limits 5.0 NTU rendering the water unsuitable for domestic use as demonstrated in figure 4.4
Figure 4.4: Mean turbidity levels of the shallow well water in Kawangware location
However, there was no significant differences (p ≤ 0.05) between the mean turbidity values for the samples from Kabiro and Kawangware sites with that of KEBS but the difference was so significant (p ≤ 0.05) between the mean concentrations of water samples from Gatina site and those of KEBS. Gatina recorded a mean level of 32.8
NTU. The elevated turbidity in this waters may be due to human activities, decrease in the water level and presence of suspended particulate matter due to the nature of the wells which tend to allow in drain water as they are not completely covered (Khopkar, 2006).
46
Water of high turbidity is aesthetically unacceptable.. It is notable that turbidity has an effect to color of the water as well as promotes microbial proliferation, thus having a negative effect to the quality of water. As indicated by Oluyemi et al., (2014),
4.2.5 Total Dissolved Solids
Mean total dissolved solids concentrations ranged from 195.6 to 603.1 mg/l with the highest values recorded at Kawangware (Table 4.2) and the lowest at Kabiro (Table 4.1).
Gatina recorded a TDS of 401.1 mg/l (Table 4.3).The total dissolved solids were within the KEBS acceptable limits of 1500 mg/l (figure 4.5)
Figure 4.5: Mean total dissolved solids of the shallow well water in Kawangware location
From figure 4.5, it is clear that there was significant difference (p≤0.05) between the mean concentration for the samples in all the sites and that of KEBS. There total dissolved solids (TDS) in this area were much lower as compared to those of KEBS. TDS
47 indicates the amount of inorganic substances in water and thus a good indicator of pollution. Elevated levels of TDS in drinking water have been associated with natural sources like sewage runoff and industrial effluent discharges in water sources (Olajire &
Imeokparia, 2001).
4.2.6 Total Hardness
The average hardness for the water samples ranged from 13.8 to 164.84 mg/l with the lowest concentration recorded at Kabiro while the highest at Kawangware site (Table 4.1 and 4.2). Gatina had 106.63 mg/l (Table 4.3). There was a significant difference (p≤0.05) between the mean concentration of all sites and those of KEBS. The total hardness values were much lower and within the KEBS permissible limit of 500 ml/l as per figure 4.6.
Figure 4.6: Mean total hardness of the shallow well water in Kawangware location
Total hardness is often measured as a combination calcium carbonate (CaCO3) and magnesium carbonate (MgCO3). According to (McGowan, 2000), the water in
Kawangware site and Gatina site was found to be hard while in Kabiro the water was soft
48 since water containing calcium carbonate (CaCO3) at concentrations below 60 mg/l is generally considered as soft. Hard water contains 120–180 mg/l (CaCO3) while more than 180 mg/l (CaCO3) is considered as very hard water. Similar trends of shallow well water having low hardness were noticed by (Ashun, 2014) in his study on water quality of groundwater in Thiririka sub location of Kiambu County.
4.2.7 Sulphate
The mean Sulphate levels ranged from 0.10 to 0.44 mg/l. The highest value of 0.44 mg/l was recorded at Kawangware while Kabiro recorded the lowest value of 0.10 mg/l.
Gatina recorded sulphate concentration of 0.3 mg/l (Table 4.1, 4.2 and 4.3). KEBS recommends maximum allowable sulphate levels of 450 mg/l in water used for drinking purposes and therefore the levels for water samples of all sites were within the acceptable levels of KEBS. There was a significant difference (p ≤ 0.05) between the mean concentration of all sites and those of KEBS. The mean sulphate concentrations of the water in this area are much lower as compared to that of KEBS.
4.2.8 Nitrate
The mean concentration of nitrates in the shallow well waters ranged between 17.9 mg/l and 18.5 mg/ml. They highest level was recorded at Gatina sub- location while the lowest at Kabiro sub- location with Kawangware recording a level of 18.4 mg/l. There was a significant different (p ≤ 0.05) between the mean concentration of nitrates in this area and those of KEBS. The mean nitrate levels of the sampled water were above the 10.0 mg/L guideline value prescribed by KEBS as seen in figure 4.7.
49
Figure 4.7: Mean Nitrate of the shallow well water in Kawangware location
The high levels (as seen in the figure 4.7) is an indication of contaminated water hence rendering it not suitable for human consumption. Elevated nitrate levels in the water may cause methaemoglobinaemia also referred to as ‘blue baby syndrome’ in infants and a cancer of the stomach in adults (WHO, 2011) The high concentration of nitrates in the shallow wells water may be due pollution by human and animal sewage through surface runoff into these wells. The use of pit latrines, poor solid waste management is the major sources of nitrates in these wells. High nitrate levels also stimulate algal growth play a role in eutrophication (Steffii et al., 2003).
4.2.9 Phosphate
Mean phosphate concentration of the sampled water ranged between 6.10 and 9.50 mg/l
The highest value was recorded at Kawangware and the lowest at Kabiro (Table 4.1 and
4.2) while Gatina recorded 6.70 mg/l (Table 4.3).There was significant differences (p ≤
0.05) in the mean of phosphate between the water samples for Gatina and KEBs.Kabiro and Kawangware the difference was not significant with that of KEBS. Phosphate
50 concentrations in the samples exceeded the KEBS permissible limit of 2.2 mg/l as seen in figure 4.8.
Figure 4.8: Mean phosphate levels of the shallow well water in Kawangware location
The extremely high levels of phosphates can cause digestive problems in humans while in water it promotes the growth of algae and weeds which use up large amounts of oxygen. These algae produce and harbor toxins which contaminate the water (WHO,
2006; WRC, 2002). High levels of this compound in the water could be due to the indiscriminate use of such detergents (Sheila, 2005).The use of pit latrines and on-site septic systems could be another cause of the high levels of phosphorous in the water since such systems leak through the soils to the waters (WHO, 2006).
4.2.10 Iron
The mean level of Iron in the water samples for Kawangware location ranged from 0.1 to
0.3 mg/l (Table 4.1 to 4.3). The highest value of 0.3 mg/l was recorded at Gatina site
51 while Kabiro recorded the lowest value of 0.10 mg/l with Kawangware sub-location recording 0.18 mg/l. There was a significant differences (p ≤ 0.05) between the Iron concentrations of water samples from Kabiro and Kawangware sites but the difference was not significant (p ≤ 0.05) between the samples from Gatina site with that of KEBS as compared in the figure 4.9.
Figure 4.9: Mean Iron levels the shallow well water in Kawangware location
However, it is notable that iron concentration in the water did not exceed the acceptable levels of 0.3 mg/l according to KEBS guidelines. The Iron concentrations from the water from Kabiro and Kawangware sub-locations were very much lower as compared to that of water from Gatina which was slightly higher. Iron has no health effect on healthy individual as it is one of the essential trace metal required by the body. However, it could impart taste and offensive odour in water at concentration greater than 0.3 mg/l (WHO,
2006).
52
4.2.11 Lead
Concentration of lead in the water ranged between 0.08 mg/l and 0.20 mg/l (Table 4.1 and 4.3). Lead levels were highest at Kabiro site and the lowest recorded at Kawangware site. Gatina sub-location recorded a lead concentration of 0.19 mg/l. The difference in lead concentrations between the sites and KEBS standards was significant (p ≤ 0.05). The lead levels elevated throughout the study area and therefore above the acceptable limit of
0.01 mg/l prescribed by KEBS as seen in figure 4.10
Figure 4.10: Mean lead levels of the shallow well water in Kawangware location
It is notable that the major source of lead pollution in the environment and water bodies is the use of leaded products such as paint, car batteries, petrol as well as industrial discharges. Improper disposal of used lead products could easily lead to water contamination through leaching to the groundwater via the soil (Tole & Jenipher, 2001).
A high level of lead in blood (above 0.04 mg/l) is known to reduce fertility especially
53 among men and raise the risks of spontaneous abortion, preterm delivery and various neurodevelopmental effects (WHO, 2004).
4.2.12 Cadmium
The mean level of cadmium in the water samples for all the sites was 0.04 mg/l (Table
4.1 to 4.3). There was a significant difference (p ≤ 0.05) between the mean levels of cadmium in all the sites with that of KEBS. These concentrations were far above the acceptable limit of 0.003 mg/l prescribed by KEBS as per figure 4.11.
Figure 4.11: Mean cadmium levels of the shallow well water in Kawangware location
The presence of cadmium in well waters may be attributed to the geological factors rather than anthropogenic pollutants input (Olago & Akech, 2001). Long term exposure to cadmium leads to bioaccumulation in the body tissues. The effect of this leads to immediate poisoning and damage to the liver and the kidneys. Cadmium also causes anaemia and hepatic disorder (Sen & Khurana, 2009).According to Muraguri (2013), the
54 presence of cadmium in groundwater in Nairobi may be explained by geological factors rather than anthropogenic pollutants input.
4.2.13 Zinc
The mean level of zinc in the water samples analysed for Kawangware location ranged from 0.02 to 0.2 mg/l (Table 4.1 to 4.3). The highest value of 0.20 mg/l was recorded at
Gatina and Kawangware recorded the lowest value of 0.02 mg/l (Table 4.2) with Kabiro sub-location recording 0.1 mg/l (Table 4.1). There was a significant differences (p ≤
0.05) between the mean levels of zinc in water from all sites and that of KEBS. The mean zinc concentrations were much lower to that of KEBS. However, the values were within the acceptable limit of 5.00 mg/l prescribed by KEBS.These results are supported by
Muraguri (2013) in his study of the groundwater in Nairobi County. The report indicated similar low concentrations of zinc in various areas within the county.
4.2.14 Sodium
The mean sodium levels in the study area ranged between 73.3 mg/l recorded at Kabiro
(Table 4.1) to 113.3 mg/l recorded at Kawangware site (Table 4.2). Gatina site recorded a mean of 97 mg/l. The difference in the sodium levels in all sites were significant (p≤
0.05) with those of the KEBS (Table 4.1 to 4.3). The sodium levels of the water were much lower as compared to those of KEBS as per figure 4.12.
55
Figure 4.12: Mean Sodium levels of the shallow well water in Kawangware location
The results showed that the levels of sodium did not exceed the guideline value of 200 mg/l according to KEBS. Sodium ions are usually a factor of the rock and soils of the area and this will determine its concentrations in the water. Not only seas, but also lakes, rivers and groundwater contain significant amounts of sodium. Its concentrations however are mainly dependent on geological conditions and levels of wastewater contamination (WHO, 2003).
4.2.15 Potassium
Potassium ion is an essential element required to maintain ionic balances in human body.
However, long term ingestion resulting to potassium ions overloads the homeostatic functions of the body and may lead to kidney problems (Marian & Ephraim, 2009). The mean potassium levels ranged between 7.9 mg/l for Kabiro sub-location and 39.8 mg/l recorded at Kawangware site, while Gatina site recorded 25.5 mg/l. The mean potassium levels of the water were within the acceptable levels of 50 mg/l according to KEBS standards as indicated in figure 4.13.
56
Figure 4.13: Mean potassium levels of the shallow well water in Kawangware location
However, the difference was significance (p ≤ 0.05) between the mean potassium levels of Kabiro and Gatina and that of KEBS. The levels of potassium in these areas were much below the KEBS recommended levels but within the acceptable limits. For
Kawangware site, the difference was not significant (p ≤ 0.134) though within the acceptable levels. The slightly higher levels of potassium seen in Kawangware site may be attributed to leakage of domestic and animal sewage into the wells because of the nature and entire hygiene conditions surrounding these shallow wells. These findings are similar to the study by Safdar, et al. (2013) on drinking water quality and its impact on residents Health in Bahawalpur City. In this study the potassium level of the water were found to be very low.
57
4.3 Microbiological properties of shallow water wells used in Kawangware location
Assessment of the microbiological quality of the well water in the study area was done by enumeration of total coliform and faecal coliform bacteria. Coliforms are the most common group of indicator organisms used in water quality monitoring. These organisms are an indication of contamination by either sewage or faecal matter. Table 4.4 and 4.5 offers a comparison of the total coliform and faecal coliform in Kabiro Kawangware and
Gatina locations respectively.
Table 4.4: Comparison of the total coliform in shallow wells water located in
Kabiro, Kawangware and Gatina locations
Units Mean KEBS Std. Dev Range p-value (2010) Min. Max. Kabiro MPN/ 1637.1 10 3079.98 330.0 9200.0 0.001 100ml Kawangware MPN/ 1013.1 10 1057.37 320.0 2980.0 0.000 100ml Gatina MPN/ 1486.6 10 1249.16 390 6500 0.000 100ml
Table 4.5: Comparison of the faecal coliform in shallow wells water located in
Kabiro, Kawangware and Gatina locations
Units Mean KEBS Std. Dev Range p-value (2010) Min. Max. Kabiro MPN/ 271.4 0 239.58 80.0 790.0 0.001 100ml Kawangware MPN/ 298.4 0 307.09 40.0 950.0 0.000 100ml Gatina MPN/ 433.9 0 350.45 10 1200 0.000 100ml
58
From table 4.4 and 4.5, it can be clearly shown that water from the shallow wells in
Kawangware location were contaminated with both coliform and faecal coliforms. The highest counts of total coliform was 1637 MPN/100 ml and was recorded at Kabiro whilst the lowest counts of 1013 MPN/100 ml was recorded at Kawangware.
At the same time, the water from all the sub-location had faecal coliforms with Gatina sub-location recording higher numbers (434 MPN/100 ml) followed by Kawangware
(298 MPN/100) and finally Kabiro (271 MPN/100 ml). The high coliforms counts may be an indication of the presence of other types of enteric microorganism bacteria other than coliforms could also be present. The presence of other microorganisms like E. coli and other pathogenic bacteria render the water unsuitable for human consumption thereby posing serious health concerns (Alotaibi, 2009; WHO, 2011). Similar studies in other parts of Kenya and Nigeria also reported the presence of coliforms and faecal coliforms in water meant for drinking and other domestic use by the residents (Otieno, et al., 2015; Adejuwon & Mbuk, 2011) and attributed it to indiscriminate human and animal defaecation, the use of pit latrines and general poor sanitation. This can be seen in
Kawangware location as earlier seen in the literature and supported by other studies such as that of Abila et.al in 2012.
The results indicated that there were a statistically significant differences of means for both total coliform and faecal coliform (p≤ 0.5) between water samples from the area and that of KEBS (Table 4.1, 4.2 ad 4.3). According to the KEBS guideline values, total and faecal coliform bacteria should be Nil in 100 ml of a sample for water intended for
59 drinking. In this study the total coliform and faecal coliform counts for Kawangware exceeded the KEBS recommended drinking water guideline value (Table 4.1 to 4.3).
These results are supported by previous studies conducted Badiyya (2013) and Ashun,
(2014), in their study of water quality of river water and groundwater respectively. These studies found out that the river and well water was microbiologically contaminated beyond the recommended values and was a potential hazard to public health. This is an indication that in most urban areas, ground water is more prone to contamination due to issues such as wrong placement of waste disposal facilities, increased presence of dumping sites and improper construction of the wells among other issues (Oguntoke et.al,
2010).
60
CHAPTER FIVE: SUMMARY, CONCLUSIONS AND RECOMMENDATIONS
5.1 Summary
The results of the study indicated that the quality of the groundwater of the study area did not meet expectations in terms of Nitrates, phosphates and was of high turbidity which would definitely affect the taste. These parameters had higher values greater than KEBS recommended standards for drinking water. The presence of considerable concentrations of cadmium and lead in groundwater samples is a major concern to public health.
However, other parameters were within the permissible standards according to KEBS requirements for TDS, conductivity, sulphates, potassium, total hardness, and zinc.
The results also revealed that the water was bacteriologically contaminated with both general coliforms and faecal coliforms which are enteric in nature.
5.2 Conclusions
1) From the study area, it is clear that the levels of the following physico-chemical
parameters were higher than the recommended KEBS standards turbidly, nitrate,
phosphates turbidity, lead and cadmium.
2) The results also revealed that the shallow wells in the area has microbiological
contamination interms of fecal and total coliforms as it exceeds the KEBS standards.
Therefore, the shallow well water in the area is not safe for drinking since it poses
great health risk to the public.
61
5.3 Recommendations
Following the findings of this research, the following recommendations are suggested in order to curb the deterioration of groundwater and to safeguard the health of the residents of Kawangware location.
1) Establish an efficient periodic monitoring system to evaluate levels of chemical
properties especially for parameters like lead and cadmium in groundwater since they
are a threat to health after bioaccumulation.
2) The level of microbiological contamination in the study area pose the leading public
health concern hence there is need for the County government to urgent provision of
adequate and suitable sanitation, proper solid waste management and clean and safe
drinking water to the residents of Kawangware location so as to safeguard the health
of the community.
5.4 Future Research
There is a need for further research on this area on;
1) Assessment of seasonal variation of groundwater quality in Kawangware location.
2) Assessment of the impact of contaminated groundwater on human health in
Kawangware location.
62
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APPENDICES
Appendix I: KEBS Potable Water Standard
PARAMETERS UNIT KEBS(KS 459-1:2010) STANDARDS pH pH Scale 6.5-8.5
Conductivity (250 C) µS/cm Max 2000
Iron mg/l Max 0.3
Sodium mg/l Max 200
Potassium mg/l Max 200
Nitrate mgN/l Max 50
Phosphates (PO4) mg/l Max 2.2
Lead (Pb) mg/l Max 0.05
Cadmium (Cd) mg/l Max 0.005
Zinc (Zn) mg/l Max 5
Total Dissolved Solids mg/l 1000
Total Coliforms MPN/100ml Max 10
Fecal coliform MPN/100ml Nil
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Appendix II: Authorization letter from the university
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Appendix III: Authorization letter from Ministry of Devolution and
Planning
Dagoretti Sub County
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Appendices IV: NACOSTI Letter
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Appendix V: Raw Data for Kawangware Location
Kabiro site
Well Time Feacal Genera TH Temp( pH Ec(µS/ TD Turbid SO4 NO3 PO4 PO Fe Cd Zn Na k No. Samp Colifor l ( °C) M)) S( ity (mg/l) ( (mg/l 4 le ms Colifor mg/l) mg/ (NTU) mg/l ) (mg taken (MPN) ms l) ) /l) (MPN) Well Morni 110 440 25.8 22.6 8.0 332.2 212. nil 0.03 18.6 0.9 0.08 0.16 0.0 0.00 74 9 1 ng 5 0 4 2 Well Eveni 90 330 27 25.1 8.0 350.0 217. 0.1 0.05 20.1 1 1 0.08 0.0 0.00 75.2 7 1 ng 0 0 4 1 Well Morni 350 370 13.52 25 8.2 296.1 189. 2.5 0.01 18.6 13.6 0.09 0.17 0.0 0.05 73.1 8 2 ng 3 0 4 Well Eveni 300 350 11.95 24.8 7.9 270.5 167. 2.6 0.01 15 14 0.08 0.14 0.0 0.03 78.5 10 2 ng 8 7 5 Well Morni 790 9200 12.9 25.2 8.3 297.2 190. 99.8 0.01 18.7 11.8 0.08 0.09 0.0 0.02 75.2 7 3 ng 9 0 4 Well Eveni 720 8600 10.8 26.4 8.3 300.2 186. 100.9 0.03 18.3 12.5 0.09 0.1 0.0 0.02 80 9 3 ng 5 1 4 Well Morni 120 500 11 25.6 8.3 314.0 201. 5.4 0.02 18.8 0.06 0.06 0.09 0.0 0.02 75 7 4 ng 3 0 4 Well Eveni 80 560 13 25 8.3 329.0 204. 5 0.04 18.2 0.04 0.06 0.1 0.0 0.01 73.5 7 4 ng 0 3 Well Morni 460 500 14.2 20.9 8.1 319.0 204. 0.5 0.03 18.8 4.4 0.07 0.13 0.0 0.3 74.6 8 5 ng 2 0 4 Well Eveni 350 490 11.24 21.2 8.0 340.0 210. 0.9 0.01 18.5 4.1 0.07 0.11 0.0 0.3 70.1 8.2 5 ng 0 8 6 Well Morni 110 450 10.9 22.2 7.8 338.0 216. 1 1 15.8 12 0.07 0.05 0.0 0.01 65.8 6 6 ng 0 0 4 Well Eveni 80 400 9.41 20.9 7.8 290.0 179. 0.7 0.08 14.3 10.8 0.08 0.03 0.0 0.02 70.4 7.3 6 ng 5 8 3 Well Morni 130 380 11.3 22.5 8.6 294.0 188. 2.1 0.01 18.5 0.06 0.07 0.13 0.0 0.08 72.8 8 7 ng 9 0 5 4 Well Eveni 110 350 10.4 20.9 8.3 280.2 173. 2.5 0.01 18.9 0.05 1 0.12 0.0 0.07 68.2 9 7 ng 3 4 75
Kawangware Site
Well Sample Feacal General TH Temp(° pH Ec(µS/ TDS( Turbidi SO4 NO3 PO4 PO4 Fe Cd Zn Na k No. colifor coliform (mg/l) C) M)) mg/l) ty (mg/l (mg/ (mg/l ( mg/l) ms s (NTU) ) l) ) (MPN) (MPN) Well 1 Mornin 70 460 9.7 28.8 7.31 289.0 185.0 nil 0.05 19.7 0.06 0.09 0.26 0.04 0.03 78 7.5 g Well 1 Evening 58 410 8.9 27.5 7.90 267.0 165.5 0.2 0.05 17.5 0.05 0.06 0.3 0.04 0.03 74.5 6 Well 2 Mornin 40 360 233.7 21.6 7.5 1335.0 854.0 0.3 0.03 18.8 14.3 0.08 0.08 0.04 0.01 154 43 g Well 2 Evening 52 320 210.5 22.6 8.2 1420.7 880.8 0.8 0.03 18.2 14 0.08 0.07 0.04 0.02 138.4 40.9 Well 3 Mornin 900 2800 129.4 19.6 7.54 814.0 504.7 1.6 0.05 18.7 0.05 0.07 0.13 0.04 0.02 103 19.5 g Well 3 Evening 750 2520 120.5 20.5 7.21 940.2 582.9 2 0.07 18.5 0.03 0.06 0.14 0.04 0.03 99.5 22 Well 4 Mornin 320 400 312.3 19.5 8.16 1562.0 968.4 12.9 0.09 18.5 14.25 0.07 0.08 0.04 0.01 133 27 g Well 4 Evening 180 360 345.26 20.5 7.96 1593.1 987.7 15 0.1 18.3 12.5 0.07 0.09 0.03 0.01 120.4 30 Well 5 Mornin 470 510 160.7 20.1 8.13 1100.0 682.0 44.3 1 18.5 40.5 0.08 0.14 0.04 0.02 105 54 g 5 Well 5 Evening 260 370 152.6 21.3 7.83 1120.6 694.8 50.1 1.2 17.9 42.8 0.06 0.1 0.03 0.02 118 46.8 Well 6 Mornin 220 450 226 19.7 7.81 118.2 73.8 7.2 1.25 18.8 0.03 0.08 0.11 0.04 0.01 133 116 g Well 6 Evening 220 390 204 21.3 7.4 1532.4 950.0 8 1 18 0.02 0.08 0.13 0.04 0.01 139 99.8 Well 7 Mornin 144 2180 225.4 20.7 7.92 1353.0 866.0 14.4 1.05 18.7 0.5 0.09 0.11 0.04 0.01 134 53 g 5 Well 7 Evening 950 2980 256.1 21 7.82 1412.6 875.8 12 0.98 17.8 9 0.09 0.12 0.05 0.01 130 55 Well 8 Mornin 90 560 19 23.7 8.34 306.0 196.0 10.8 0.04 18.5 1.5 0.08 0.01 0.04 0.01 77 7.4 g 5 Well 8 Evening 50 510 23 23.3 7.90 296.2 183.6 12.5 0.06 18.2 1.8 0.06 0.02 0.03 0.02 76 6.9
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Gatina Site
Well Sample Feacal General TH temp(° pH Ec(µS/M)) TDS( Turbidity SO4 NO3 PO4 Pb fe Cd Zn Na k No. coliforms coliforms ( mg/l) C) mg/l) (NTU) ( mg/l) ( mg/l) ( (MPN) (MPN) mg/l) Well 1 Morning 10 440 25.4 22 8.24 325.0 208.0 50.1 0.7 18 12.5 0.08 0.12 0.04 0.2 77 7.5 Well 1 Evening 21 390 28 23.4 7.90 561.2 347.9 48 0.8 17.75 11.1 0.09 0.1 0.05 0.3 75.8 9 Well 2 Morning 1200 2840 179 21.1 8 1128.0 722.0 70 0.8 19.55 0.03 0.07 0.09 0.04 0.03 134 54 Well 2 Evening 1150 2740 196.2 22.5 8.3 1254.6 777.9 75 0.75 19.8 0.02 0.09 0.08 0.06 0.05 129.8 55 Well 3 Morning 810 1440 138 22.5 7.32 934.0 598.0 45 0.9 19.8 4.4 0.07 0.08 0.04 0.06 102 45 Well 3 Evening 785 1100 145 21.8 7.8 789.3 489.4 48 1 19.5 4.6 1 0.09 0.04 0.05 99.8 47.1 Well 4 Morning 440 850 187 21.7 7.96 747.0 478.0 25.2 0.04 18.75 12.5 0.08 0.09 0.04 0.01 98 27 Well 4 Evening 650 920 172.6 22.6 7.6 854.6 529.9 28 0.05 19 11.9 0.06 1 0.03 0.01 100.1 30.5 Well 5 Morning 360 980 24.8 29.5 9.74 312.0 200.0 16.5 0.07 18.5 4.5 0.08 0.07 0.04 0.04 72 7.5 Well 5 Evening 400 800 25.6 25.4 9.30 196.3 121.7 18.3 0.08 18.5 4.5 0.07 0.08 0.04 0.03 75 9.8 Well 6 Morning 980 1040 13.8 30.1 9.88 351.0 225.0 10.2 0.02 18 4.5 0.09 0.27 0.04 0.04 82 9.5 Well 6 Evening 920 6500 12.9 25.4 9.5 210.3 130.4 10.7 0.01 18.3 3.9 0.06 0.24 0.06 0.05 85 10.2 Well 7 Morning 140 600 11.9 18.5 9.86 308.0 197.0 0.6 0.03 18.6 1.5 0.07 0.14 0.04 1.2 72 7.5 Well 7 Evening 120 540 12.1 20.5 9.4 568.9 352.7 1.2 0.04 18 1.3 0.05 0.16 0.05 1 68.7 10.9 Well 8 Morning 170 1950 141.6 17.5 8.17 909.0 582.0 3.4 0.04 18.6 1.35 0.11 0.26 0.05 0.14 101 53 Well 8 Evening 100 1700 136.4 18.3 7.90 995.7 563.6 2.8 0.02 18.2 1.08 0.12 0.3 0.03 0.2 99.8 49.9 Well 9 Morning 110 440 19.6 19.4 9.5 319.0 204.0 25 0.03 18.8 11.65 0.07 0.13 0.04 0.02 74 9.5 Well 9 Evening 120 460 20.1 19.1 9.4 296.4 183.8 23 0.03 19 12.8 0.06 0.11 0.05 0.01 69.8 11 Well 10 Morning 220 1360 152 20.3 7.75 117.0 715.0 18.7 1 18 12.5 0.08 0.84 0.04 0.02 133 45 Well 10 Evening 430 1300 134.1 21.3 7.2 239.4 148.4 16 1.5 17.8 13.6 0.07 0.86 0.04 0.03 142.2 47 Well 11 Morning 630 1870 152.3 20.3 8.05 770.0 493.0 20.5 0.08 18 4.45 0.08 0.11 0.04 0.03 82 19.5 Well 11 Evening 450 1720 124.6 21.5 7.9 924.3 573.1 18 0.1 18 5 1 0.15 0.05 0.03 79.2 22 Well 12 Morning 310 1590 234 20.6 7.57 708.0 453.0 65 0.06 18.1 1.55 0.08 0.08 0.04 0.03 132 19 Well 12 Evening 280 1550 211.4 21.6 7.90 864.2 535.8 78 0.08 18.2 1.6 1 1 0.05 0.04 130 17.8 Well 13 Morning 280 2320 146.5 18.2 8.20 470.0 301.0 60 0.08 18.8 14.4 0.1 0.1 0.04 0.08 105 19.3 Well 13 Evening 200 2380 152 20.1 8 481.4 298.5 75 0.1 17 15.8 0.2 0.3 0.06 1 101.9 19.8
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