chapter WATER RESOURCES AND SUSTAINABILITY

© The Author(s) 2019 P. G. Rowe and L. Hee, A City in Blue and Green, 04https://doi.org/10.1007/978-981-13-9597-0_4 04 I innovation as by way of overall conceptualization. conceptualization. by of way overall as innovation technical specific not much comes approach so from however, supply water domestic Singapore’s in innovation, and genius real The by 2030. use daily in person per of 130 liters goal to the closer getting is Singapore today Indeed, long run. the supplywater in sustainable component to achieve critical equally an Tap, National fifth the as imagined be could This of use. water source atthe conservation individual of form the in largely reduction, demand successful and by of way active performance improved promotes actively also government side, the demand of seawater. the On desalination and technologies, cleaning other and membrane water, involving NEWater, of reclaimed brand Singapore’s so-called Two of supply are sources demand. compensatory city-state’s of the face in not feasible are approaches supply and treatment storage, water conventional Therefore, more area. catchment and land limited proper, a has cities Singapore the than elevations athigher also areas, outlying in dams in resources abundant their with Australia, in or Melbourne U.S. the in Boston world, like the in places other unlike rainfall, of annual terms in rich water Although drains. and canals of rivers, anetwork via 17 to Singapore’s rainwater reservoirs channeling and some supply, by of way collecting largely provides catchment’ water ‘local to importation, addition In supply strategy. its as taps’ national ‘four its called are what upon dependent is Singapore At present outcome issue. and single to this abeyance in knee’, to speak, so atthe ‘bend concern national of matters other all that important strategically so 2009. of supply as or of so overall percent for 40 account Malaysia from sources imported though even end, will Malaysia neighboring with agreement water by 2061 remaining Singapore’s when this to achieve expected it is Indeed, concern. national of strategic is use to supply water and regard with attractiveness, sustainability of Singapore of Singapore sustainability attractiveness, and identity, equality of national service the in clean’ and to ‘green n addition 1 Moreover, sustainability in this regard is is regard this in Moreover, sustainability 59 conjunction with ‘used water’ instead of ‘waste water’ water’ of ‘waste instead water’ ‘used with conjunction in loop of aclosed made is use elsewhere, as system supply and treatment storage, raw of alarge Instead 43. augments and ‘tops up’ so to speak, necessary necessary to speak, up’ so ‘tops and augments NEWater further production with together and desalination Finally, lessened. clearly is resources energy in for water another in of one dependency trading the not self-sufficient, completely Though dependent. to be continues Singapore where gas, and oil of energy, like sources onload imported the helps lessen also of course, augmentation, This efforts. re-cycling the in required pumping requisite the help drive and capacities to augment current power of electrical co-generation and waste from extraction of carbon form the in re-cycled being energy-water nexus, of the island city-state aland-scarce as lacks Singapore which devices storage for large need the obviating once, thus of more water than drop every recycle and water of used drop every collect runoff, of rainwater drop every almost to gather are system loop closed of the principles fundamental The island. the across network sewerage and drainage the to expand to continue for Singapore foundation effectively of conveyance system sewage re-cycling. constantly is that T

he colonial legacy of a separated storm water and and water storm of aseparated legacy he colonial WATER (L/person) 150 100 200 50 0 HOUSEHOLD WATERCONSUMPTION SINGAPORE’S DOMESTIC 1994 2002 the sewage stream is is stream sewage the 2012 . 2015 I n terms n terms s ets the the ets 2030

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY liters perperson overall domestic water supply. Several technically conveyance systems will ensure success, probably sophisticated desalination plants have been built well before the 2061 deadline. In addition, significant or are under construction at various ends of the aspects of the radical overall approach seem to be island to perform this function. As mentioned it is transferable to other water-scarce urban situations the co-ordination of use and implementation of this elsewhere in the world. What is excluded from this multi-source approach and the radical re-thinking depiction, however, are virtual water flows ascribed of conventional municipal water storage and supply to Singapore from elsewhere in the world in order that has been Singapore’s signature international to support agriculture and industrial products used contribution and where it truly leads, rather than by Singaporeans. While likely to be sustainable with in the membrane, desalination and other treatment regard to important elements of domestic demand technologies per se. Furthermore, although not like household use, the city state is not and likely will completely implemented at this writing, sufficient not be fully sustainable with regard to virtual water proof of concept and several working plants and consumption, like many other nations in the world. a. SINGAPORE’S CONSTRAINTS AND OPPORTUNITIES IN WATER RESOURCES

Largely due to its relatively small size and lack of a the Punggol and Serangoon Reservoirs the drainage full complement of natural resources, Singapore faces catchment area now covers roughly two-thirds of a number of constraints as it attempts to achieve the national territory.4 By contrast, Melbourne in water sustainability by 2061. By contrast, there are Australia, another city with a comparative emphasis also some advantages or opportunities that can on ‘green and blue’ developments leveraged its spatial be exploited further. At present the land area of advantage to easily tap into its protected and forested Singapore is 722.5 square kilometers, including some catchments to harvest water stretching along the 140 square kilometers of reclaimed land, or around Great Divide, a substantial area in the middle of the 24 percent of the land area since 1959, constructed State of Victoria. Recently, however, climate change mainly in the west and east.2 Despite this relatively and drought conditions revealed some vulnerabilities small area and dense land occupation at around 7,042 with regard to adequate supply, despite the large inhabitants per square kilometer, Singapore has its latent capacity of the catchment areas.5 rainwater and run-off storage capacity appreciably through construction of reservoirs in the centre Unlike other large cities, Singapore does not enjoy of the island and at river mouths. Early stages of abundant groundwater supplies. Indeed, as described this were described in chapter 2, but more recent earlier, serious consideration of groundwater as a advances have been made from fourteen reservoirs potential source of constant supply has been ruled in 2005 to seventeen reservoirs as of today.3 With out, even though the PUB continues to monitor the recent building of the Marina Barrage and both and look into the possibility.6 By contrast annual

60 44. in fluctuations to this, acorollary As processes. treatment problems for reliable potential posing well, as services water estuarine and of reservoir compositions chemical other and salinity relative the influence also can weather out The entirely. ruled be 1963 in but cannot uncommon be may island the afflicted one that the like droughts, term Longer catchment. and rainfall of intense bouts up between dry can supplies where precipitation, in valleys and peaks the are conditions monsoonal tropical the with however, issue, One island. the water, surrounding sea is as location, tropical Singapore’s in year per mm 2,400 at around abundant relatively is rainfall Western Catchment AND DRAINAGESYSTEM MAPS PERTAININGTO SINGAPORE’S CATCHMENT Central Catchment Easter Catchment Catchment Boundaries 61 of water, but is expected to double with technical technical to double with of water, but expected is meter cubic per kwh 0.66 about is treatment water for meter domestic cubic per requirements energy moment At the treatment. to down-line regard with particularly system, sewage storm-water and dual and of aseparated legacy British the from benefits state city the though, By contrast, technologies. of desalination use the with sector,water especially its in resources energy costly often and imported largely between atrade-off must make Singapore Clearly plants. of treatment efficiencies operating effect can of salinity levels at varying and processes desalination with associated demand electrical Drainage Map 0 2.5 Changi Geylang Punggol Stanford Marina Bukit Tmah Kallang Woodlands Pandan Kranji Jurong 5 10 Kilometers

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY shifts towards desalination and water reuse, before in commodities of various kinds, such as the ratio reaching a level of something like 0.75 kwh per cubic of the total volume of water used to the quantity meter in the longer term.7 To put this in context, of production.10 More basically, a water footprint it has been estimated that about two percent of the has three components. They are: the green water Singaporean electricity demand is already dedicated component or the volume of rainwater evaporated to water and treatment processes.8 or incorporated into products; the blue water component or volume of surface or groundwater Singapore’s concerted efforts towards sustainability evaporated or incorporated into a product or in domestic water consumption, however, are returned to other catchments or the sea; and the dwarfed by the imputed virtual water components gray water component, or the volume of water of food and industrially produced products. At needed to dilute loads to such an extent that they present this seems to amount to about 20 times reach certain water quality standards.11 Anyway, the current blue water supply. Here virtual water Singapore’s small scale, particularly in relationship is a term that embraces the amount of water used to its largish population effectively precludes it to produce a certain good or product. It was first reaching a sustainable condition with regard to introduced during the 1990s to account for the virtual water. As described in chapter 2, during limitations of water scarce regions which imported times in the past Singapore was far less numerous food grain grown with other’s water.9 From this the in population and did, in fact, reach levels of self- broader concept of a water footprint was developed, sufficiency in food production, mainly from small allowing calculation of the amount of virtual water family-owned farms.

2010 2060

DOMESTIC 45% 30%

NON-DOMESTIC (POTABLE) 33% 42%

NON-DOMESTIC (NON-POT.) 22% 28%

NON-DOMESTIC (TOTAL) 55% 70%

PER CAPITA 154 LITRE/DAY 130 LITRE/DAY (2030)

TOTAL (MILLION GALLONS/DAY) 380 (100%) 860 (100%)

45.PROPORTIONS OF TOTAL AND SEGMENTED WATER USE, 2060 PROJECTION

62 of water. meter cubic per kwh 0.25 ataround small quite also is tap of this footprint energy The area. nation’s of land the to two-third area catchment drainage water the expanded and 17 reservoirs of atotal developed successfully has Singapore reservoirs. and courses water main the from away and island of the southwest and south the in concentrated are activities industrial green’.and Today and development of harbor ‘clean being Singapore in interest abiding Yew’s Kuan to Lee 2and chapter in described Republic, early of the programs clean-up the to back goes also tap of this viability of the aspect Aclear earlier. described system storage run-off and rainwater Singapore’s and catchment on rainwater relies tap water second The Taps. National additional of the establishment the through undertaken being is supply. This of water sources the 1970s the to diversify in efforts its to intensify begun had and sustainable, more to be need felt the government Singapore water, of imported the source the having Despite processes. treatment water ofway conventional by freshwater from produced is water drinking 2013. in al. et Lenouvel by assumed as year per meters cubic million 250 to corresponding demand, water Singapore’s of 40% to provide estimated is tap This earlier. described briefly of agreements, water a series under Johor Malaysia from water in importing consumption. water local to manage efforts plus concerted taps, four its through sustainability water towards progress for relies side, Singapore resource the On b. 14 SINGAPORE’S FOURNATIONALTAPS 12 The first tap is supplied by supplied is tap first The 13 In this process quality quality process this In 63 down the cost of membranes, that PUB revisited the the revisited PUB that of membranes, cost the down brought had advancements technological when 1990s the in only It was unreliable. and costly too were then technologies the however, because off not take it did treatment, and on reclamation water experimenting started Board 1974 the in Utilities then-Public when back way NEWater The started journey needs. water of Singapore’s percent supply up to 40 can currently This NEWater Initiative. so-called the and reuse on water 2003, since relied, has tap water third The cannot pass though the membrane. In other words, other In membrane. the though pass cannot etc., pesticides, hydrocarbons, aromatic by-products, disinfection sulfates, chlorides, nitrate, metals, heavy viruses, bacteria, as such contaminants undesirable Consequently, through. to pass molecules water like molecules small very allow only it which in pores small very has membrane semi-permeable This used. is membrane asemi-permeable where osmosis, reverse as known is NEWater process production of this stage second The molecules. organic and salts dissolved only contains membrane the through goes and viruses some bacteria, disease-carrying particles, colloidal out solids, to filter membranes through passed is microfiltration. as known is process of the stage first The standards. of highest the meeting water drinkable in resulting of stages, asuccession through effluent, including water, used for treating process aproduction involves NEWater water. Fundamentally, of reclaimed of NEWater, creation to the led brand Singapore’s that amilestone Bedok, in plant reclamation water ademonstration constructed and designed eventually 2000, in engineers, study, the feasibility thorough and technologies cities’ of other study overseas Through recycling. water of large-scale possibility protozom cyots protozom 15 It is when the treated used water water used treated the when It is . The filtered water that that water filtered . The

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY NEWater is reverse osmosis water and is relatively the three desalination plants combined amounts to pure and contains negligible amounts of salts and 130 mgd that can meet up to 30% of Singapore’s water organic matter. At the onset of the third stage, the demand,22 but with high amounts of energy input at water is already of a high quality and it acts as a about 4.10 kwh per cubic meter of water, or about 74 further supply back-up to the reverse osmosis. In this percent of the total amount of energy expended by stage ultraviolet disinfection is used to ensure that Singapore’s water sector.23 There are also different all organisms are inactivated and the purity of the configurations of desalination. In the Singaporean water product can be guaranteed. Before storage of context one of the most promising is the variable NEWater in tanks, the water balance of pH and the salinity desalination concept, devised to respond to addition of some alkaline chemicals takes place to the weather-variable conditions within catchment restore the acid alkali pH balance. It is then ready to areas described earlier, especially in estuarine be piped off to a wide range of applications mainly circumstances. There levels of salinity can vary for non-potable use by the industrial sector such as substantially, such that harvesting needs to respond wafer fabrication plants which require ultra-clean to the variation and in a timely fashion. Instead of water. About 2 percent of NEWater is injected into remaining idle during periods of high overland flow reservoirs to blend with the raw water, before it is and freshwater infiltration into a catchment area, the sent to the conventional waterworks for treatment desalination mode is altered in response.24 Overall, and supply to customer taps.16 Such a process of the process still involves screening, microfiltration, indirect consumption of NEWater, in addition to reverse osmosis and disinfection, as shown in the extensive public education and outreach efforts, is accompanying diagram, but with modes that respond part of PUB’s strategy to overcome aversion by the to the levels of total disposable solids and salinity public to the reclaimed water.17 The accompanying levels to product potable water that meets WHO and diagram illustrates the process of NEWater USEPA’ Drinking Water Guidelines and Standards’.25 production. The tertiary wastewater treatment The advantages of the variable approach include: involved with NEWater consumes relatively high much lower energy consumption through the mode amounts of energy due to the intensification of switching and also significantly lower capital an the nutrient removal process.18 In some places, operating costs. for instance, such advanced wastewater treatment processes are highly energy intensive, with demand Other versions of desalination technology consist ranging from 0.39 up to 3.74 kwh per cubic meter of essentially two kinds. They are: reverse osmosis of water. In Singapore the energy demand is on the and combined electrodialysis-electrodeionization order of 0.95 kwh per cubic meter of water, not very processes. Reverse osmosis has been around since the high but, in aggregate, significant.19 1970s and was the technology, discussed in chapter 3, though defective, that gave impetus to Singapore’s The fourth water tap relies on seawater desalination conviction to pursue non-conventional sources of with, in Singapore, the commissioning of its first water supply. The process involves forcing seawater two plants in 2005 and 2013, with water production against a water permeable membrane which prevents capacities of 50 and 115 million cubic meters per dissolved salts and minerals from getting through.26 year.20 Currently, the share of the desalination tap in However, it has a couple of inherent economic and water supply has been estimated to be approximately technical limitations that will curtail its future use. 8% of the total, with an assumption of imported First, the feed pressures are very high requiring water providing 40% of the water supply and substantial energy. On average 3.5 kwh per cubic rainwater harvesting at 30% .21 The stated capacity of meter of water are required. Second, pressures

64 46. 47. SINGAPORE’S FOURNATIONALTAPS NEWATER DIAGRAM international standards accordance with of usedwaterin Collection andtreatment WATER RECLAMATION PLANT 17 Reservoirs Johor River 5 NEWater factories Sea Collection ofusedwater CATCHMENT AREA network (515km) Transmission in thisstage including somebacteria Filtering outparticles MICROFILTRATION treatment plants 3 desalination 8 PUBwater reservoirs 5 service plants distribution network Transmission and (5,4000km) 65 this stageishigh-grade removed. Thewaterafter Contaminants are 650 accounts reservoirs 14 service REVERSE OSMOSIS premises directly or throughhigh installations 77 pumping reclamation 1.5 million level tanks NEWATER 4 water plants Sea restore pHbalance. Chemicals areaddedto from thewater. organisms areeradicated ensures anyremaining Exposure toUVlight DISINFECTION ULTRAVIOLET and theDeepTunnel Used waternetwork (3,400km ofsewers Sewerage System)

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY FLOTATION UNIT REVERSE OSMOSIS UNIT STORAGE

Chemicals are added to The pre-treated seawater is The treated water is accumulate impurities pumped at high-pressure pumped to service into bigger particles, and through semi-permeable reservoirs and air is pumped to make membranes to separate distributed to homes. lighter particles float to dissolved solids. The same the surface for easy technology is used for the removal. NEWater process, except that the water passes through the reverse osmosis membranes twice.

SEA WATER

INTAKE SCREENS GRAVITY SAND UNIT POST TREATMENT

Seawater flows into the The water is filtered The water is deminer- plant through an open through sand to alised; lime is added to seawater intake structure remove heavier adjust the pH level and with mechanical rake particles. improve the taste, course screens. Chlorine Chlorine is used to is added to inhibit disinfect the water, and marine growth in pipes Fluoride is added for and other structures dental wellness. throughout the system.

48.DESALINATION DIAGRAM

(-) CATHODE

Inlet Water Product

Concentrate

(+) ANODE

49.MICROFILTRATION SCHEMES AT WORK

66 economic crisis she worked as a chemist for Glaxo for Glaxo achemist she worked as crisis economic Asian of the onset the During business. in career a of way making astrong was this thinking of Singapore, University National at the a chemist as trained she then to go business into Determined age. early at an streets the in selling and factory arattan in working achild, as life her business off She started Lum. Olivia is industry water the in entrepreneurs proponents and main ofOne the to produce. cheaper to be likely seem of which both membranes, nano-filtration and membranes ceramic including investigation, serious under also are technologies of membrane innovation higher. Further is that rate recovery product awater and of lower quality water of feed atolerance expenditure, lower energy It includes: obvious. fairly are osmosis over reverse method electrodialysis-electrodeionization combined of the advantages The of transfer. efficiency the increase which resins of exchange use the with but potential electrical with charged membranes semi-permeable through of solutions transfer the up involving takes electrodeionization Then by electrodialysis. removal lowbut too is for further present remains content that salt in results modules of electodialysis series the However, through flow ions. salt with aconcentrate with removed along ions salt with water product the into separates seawater The voltage. current adirect with charges membranes exchange ion semi-permeable through them by transferring charge electrical on their ions based removes salt selectively which process separation electrical an is electrodialysis Technically, established. they which competition Challenge’ ‘Singapore 2007 of the Technologies, apart as Water Siemens as known Technologies, previously by Water pioneered Evoqua was technique this of meter water. cubic per Singapore In 1.8 kwh at testing consuming, energy less far are schemes electrodialysis-electrodeionization the contrast By replacement. constant relatively requiring of membranes deterioration serious cause also can 27 28

67 constructed some 1,000 plants of various sizes all all sizes of various plants some 1,000 constructed successfully has Hyflux business, in some 29 years After plant. desalination second country’s the build bid PUB’s tender to won for the the again Hyflux Tuas. -in Plant Subsequently, Desalination Singspring -the plant desalination seawater large-scale first Singapore’s to build awarded year, was following the in and Seletar NEWater in PUB by the plant third Singapore’s to build acontract awarded was Hyflux 2002, In technology. of membrane potential the realizing she worked towards one technician, and clerk of one astaff only with off Starting Park. Industrial Tampines the in enterprise for an capital start-up the order to raise in assets personal using firm, her current of version Hyflux, early an Hydrochem founded and 1989 In Glaxo she left technologies. water in interested became and Pharmaceuticals PUB has been very active in these regards, especially especially regards, these in active very been has PUB the Indeed, use. family and for individual strategies and technologies water-conserving of various impact the about explanations elaborate with exhibitions including efforts, education public intense around 2015). of 151 (as level of person per day per current liters its from down 2030 in day per of 130average liters to an household demand domestic of reducing aim the with management, and of conservation water program astrong upon embarked also Singapore mentioned, as taps, four to these addition In water. of reused reliability and safety the in public’s confidence the to gain was overcome to be needed that hurdles major ofOne the health. public and cleaning business: resource water of the aspects important two the foron her what are concentrates still and brand ELO the under water rich of oxygen- brand her own producing in involved she is At present concerned. were projects large-scale as far it map, were, as on as approach the general put the did technologies desalination associated and technology membrane inventing not literally though efforts, Lum’s industry. treatment water offorefront the very at the put Singapore world helped over and the 29 Primarily conservation efforts have revolved revolved have efforts conservation Primarily

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY among and with children a route that appears demand by 2061. This will also add to the needed to catalyze further involvement among adults as energy budget, though with greater efficiency. well.30 In the future, the present conservation The Singapore Government aims to increase goals appear to be realistic. In addition, among the water catchment area to 90% of Singapore’s the taps, NEWater seems likely to account for 55 land area, up from about 66% of current water percent of domestic water needs by 2061 with 40 catchment area. Overall, the goal of sustainability percent through five plants at the end of the year by 2061, if not before, appears likely if not almost and desalination will likely supply 30 percent of certain to be achieved.

FEED

Na+ Cl Na+ Cl

Na+ Na+

Na+ Cl Na+ Cl

Cl Cl H+ H+ OH- OH- OH- OH- OH OH H+ H+

PRODUCT REJECT PRODUCT CEM

AEM

Cation Exchange Resin

Anion Exchange Resin

50.DIAGRAMS OF ELECTRODIALYSIS – ELECTRODEIONIZATION

68 the lowest globally. Consequently, the break with with break the Consequently, lowest globally. the among at 5percent, stands leaks, through lost water of for WaterUnaccounted consists (UFW), mainly the where system, loop a closed into networks distribution and plants technologies, tap four the of arrangement the is sustainability water domestic to approach of Singapore’s aspect radical and crux the diagram, accompanying the in indicated As c. 51. TUAS WATERTREATMENTMEMBRANETECHNOLOGYATWORK SINGAPORE’S CLOSEDLOOP SYSTEM 69 capacity, making the entire system viable over time, over time, viable system entire the making capacity, storage water useable the does so populations, expanded to serve increases network the as Also, world. the in countries by many adopted often plants treatment conventional and of reservoirs areas large for need remove the theoretically which system, overall the of in water reuse and re-cycling constant the to supply water is approaches conventional other

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY in theory if not in practice. Central to Singapore’s from reverse osmosis by membrane bio-reactors. approach is naming and popular acceptance of ‘used The PUB has also increased the integration of energy water’, in lieu of ‘waste water’ and because of this, a systems in water facilities again in three ways. capacity to re-cycle and reuse almost every drop of First by involving increased optimization of biogas water on the island. Also key here is the harvesting production from sludge digestion in used water and use of water in and from urban rather than more treatment plants. Second by using production of pristine circumstances. This is considerably different energy through turbine technology in desalination from conventional water supply regimes in places plants. Third by offsetting operational costs of like Boston and Melbourne, where water harvesting producing clean water and electricity through system is largely if not totally confined to catchment areas integration between a power generation plant and which are preserved as such and separated away a water reclamation plant. Independent study has from potentially contaminating other uses. This shown that the long-term target of 0.75 kwh per change in the spatial logic of water harvesting and cubic meter of water seems likely to be achieved, potable water reuse is both a liberating and persistent especially with suspension of reverse osmosis and feature of the Singapore approach. It does not mean, reliance on breakthrough innovation in ion exchange however, that the nation’s catchment areas that have and biometrics.33 been well-defined and at least partially protected for years will fall away as sources of water supply for As mentioned here, the evolution of the Singapore they will not. It also means that reservoirs for long- water convergence and treatment system has been term diluting retention of large volumes of water, incremental from its early trials and beginnings like the Marina Barrage, close to very urban adjacent even as far back as the 1970s. Indeed, it is through land uses and sources for NEWater production will the various steps in the process, the discoveries be maintained and become something of a new norm made and the successive improvements incorporated in the closed loop system of reuse and delivery.31 that Singapore has made an indelible mark on the In short, the indigenous three taps of Singapore’s contemporary enterprise of the urban water sector supply resources will remain with the emphasis in and water industry. Currently another instance of the use of one over the others determined by other this is being made through the island-wide Deep related factors such as energy use and technological Tunnel Sewage System (DTSS) under the auspices of reliabilities. the PUB. Before its design and implementation the used water system of Singapore involved six water The reduction of energy dependence in the water reclamation plants and some 130 sewage pumping sector has been taken up by local authorities, largely stations. With the DTSS the scattered pumping under the umbrella of the Water Industry Program stations can be progressively phased out and replaced Office in partnership with the private sector and with a single large diameter tunnel which conveys university research capacities. This involves at used water flow by gravity. The used water is then least three initiatives. The first is reduction of pumped up only once at a centralized pumping desalination energy needs through grant research station located at two water reclamation plants by Evoqua Water Technologies among others. The located at the eastern and western part of Singapore. second involves an increase of water catchment area The scale economy of this approach is cost effective to 90 percent of the island territory and with the compared to the older and existing infrastructure. use of variable salinity technologies to collect and By reduction of surface facilities it also frees up treat water from estuaries.32 The third is reduction valuable land for other higher-valued development. of sludge processes, also involving pre-treatment It also ensures adequate long-term convergence

70 52. and rock the through machines boring tunnel using constructed are pipes tunnel large These diameter. in meters to three 0.3 around sewers, of linked kilometers 60 and diameter in meters to six some three tunnel, of deep kilometers 40 of comprised also It is island. of the west the in atTuas NEWater day per capacity gallon million plus 25 plant day per 176 gallon million similar a feature 2014, in commenced phase, will second The sewers. of linked kilometers 60 and sewers tunnel of deep kilometers up of 48 made is and island of the east the in day per gallons million of 176 plant Changi the comprised 2008, in completed phase, first The phases. two in pursued being is DTSS of the water.for used Construction super-highway the becoming is DTSS the effect, In system. water used resilient and reliable robust, amore presenting while capacity, treatment and SINGAPORE’S WATERCLOSED LOOPSYSTEM Collection ofrainfall 17 RESERVOIRS RAIN TREATMENT PLANTS 3 DESALLINATION Treatment ofraw to potablewater 8 PUBWATER PLANTS SEA 35 34

Direct non-potableuse 71 and water management approaches are also being being also are approaches management water and of energy Integration Tuas and west. the east in the in Changi north, the in at Kranji facilities NEWater and plant reclamation treatment three of location the and system of the aspects present diagrams and map accompanying The system. management asset future and construction during of coordination advantage (BIM) to take Modeling Information Building use will undertakings engineering of these Management sewers. link the with atjunctions located facilities management air through mitigated is nuisance odor tunnels, the in present also airflow With adequacy. structural of for monitoring tunnels of the lining the into embedded be will cable optic fiber and inspection for used be will vehicles Remote operated island. the routes through of their substrate mixed-face intertwined with the DTSS, as described earlier. described as DTSS, the with intertwined HOUSEHOLD 5 NEWATER FACTORIES INDUSTRY RECLAMATION PLANTS Treatment of Collection of used water used water 4 WATER

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY 53.MAP OF THE DEEP TUNNEL SEWERAGE SYSTEM

54.SECTION OF THE DEEP TUNNEL SEWERAGE SYSTEM d.

STOCK-FLOW DEPICTIONS

Looking across available data, the propagation of capita water use was 151 liters per day per person on domestic to non-domestic water use in 2010 or average. Projections show that these numbers change thereabouts was 45 percent to 55 percent, with appreciably for 2061 with over a doubling of total the latter number comprised of 33 percent potable water demand and an apportionment of 30 percent in water to 22 percent non-potable water. The bulk domestic use and a rise to 70 percent of the total for of water use was in domestic at about 43% whereas non-domestic use, which consists of both commercial commercial and industrial each takes up about 26% and industry use.36 The per capita use is estimated of Singapore’s water use. As noted earlier the per to be 130 liters per person per day, based essentially

72 up by Charles Minard in 1889, in Napoleon’s Minard depicting up by Charles drawn was type of similar diagram notable Another of condensation. amounts massive and flare alternator way, smoke, the as friction, along such process the from emanating of waste forms various side, and right-hand far on of the propulsion form the in output side with left-hand on the of inputs band awide he depicted diagram simple 1898. arather In in inputs to energy regard with efficiencies relative its and engine steam the to describe of diagram type this used who originally Sankey Riall Phineas Henry of Mathew name by the captain Irish for an named are diagrams flow These case. this in uses domestic and commercial of industry, form the in production of results to the inputs raw initial from of resources, quantities of different flows to the proportion direct in shown of areas width the with diagrams, flow are here, depicted as such diagrams, These Diagrams. Sankey called are what through is land, and energy like well, as resources to other relationship in and for use water of way accounting Another by met desalination. be will demand water of the up to 30% while demand, water of the of NEWater up to 55% to meet capacity the increase to aimed Johor Singapore from water of and piped absence the with dramatic also are projected, as least island. the across loop water of the closure to the testament afurther percent, five only is inventory this in for water of unaccounted amount The use. building and for industrial distributed evenly again percent 23 with percent, at 54 to household use strongly weighted again also of for use percent 28 accounted Johor from by sales Water use. directly piped building and for industrial each percent 20 and household use for percent 60 with direction, opposite the in directed is use for of 25 total percent accounting desalination, household use. for percent potable six only with favor of industry, in heavily proportioned also NEWater is for use 19 accounted of total percent of supply, of sources 2010 taps four in to Singapore’s Returning by 2030. reached to be likely on alevel 38 Changes in these proportions in 2061, in at proportions these in Changes 39 37 Water from 40 40 73 economy. This kind of mixed stock-flow diagram diagram stock-flow of mixed economy. kind This Singaporean to the importance relative showing of away and consumption for physical a proxy becomes expended words, dollars other In usage. physical literal than rather utilities, for its sector use by each expended amounts dollar to reflect data of sufficiency and however, was, There availability demand. energy and water land, across Singapore for diagram Sankey meaningful a complete and to construct data available accurate not sufficiently was there writing, of this time atthe Unfortunately, equivalent. or its efficiency in losses and outputs corresponding with along inputs resource basic other and energy to represent largely subsequently, used diagram. Sankey’s pre-dating actually and Campaign Russian higher, so that electricity sales dwarf water sales. water dwarf sales electricity higher, that so much is pricing electricity out that it turns critical, are utilities both Though purposes. residential and to industrial devoted is Much more land patterns, development commercial to dense speaks which significant, still is consumption resource their buildings, to commercial devoted of land share asmall while to note that interesting It is use. land of Singapore’s aportion only constitute which sites, industrial and commercial routed to residential, are water and Electricity of industry. that than greater to be appears users by commercial expenditure total the of electricity, kilowatt-hours fewer consume users commercial while so substantial, is sector for each structure rate in difference the sales, electricity For in example, consumption. to similar equate not necessarily does expenditures similar noted that it must be although sectors, all among uses. other and transport residential, industrial, to commercial, on sales based Singapore, in electricity and water on shows expenditures chart this More specifically, context. Singaporean constrained ahighly in land and utilities among showgenerally, arelationship more and, uses land to specific tied fact, in are, flows resource that idea useful the introduces also 41 Nevertheless, these diagrams have been been have diagrams these Nevertheless, 42 42 There is relatively balanced usage usage balanced relatively is There

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY However, as projected in 2061, Singapore’s water public education and engagement programs for demand is likely to double, and projected demand schools homes and commercial offices to encourage for both industry and commercial would take up water conservation practices. In 2009, PUB also roughly 70% of the demand, with households taking implemented the mandatory Water Efficiency up 30% of the demand. This could be a combination Labelling Scheme, which requires manufacturers of the expansion of the industry and commercial and retailers to inform consumers of the efficiency sector in the future, while more effort needs to be level of their products, such as washing machines, put in place to encourage water conservation among taps, urinal flush valves and so on. Unaccounted households Nonetheless, PUB has consistently for water remains low at 5%, which is among the been able to achieve the target it has set to reduce lowest globally. Dissipated energy is relatively high the nation’s water consumption per capita through and correspondingly larger than unaccounted for

return from jackets engine friction

WORK effective

leaving boiler heat in steam work

ECONOMIZER ENGINE STEAM PIPE flue BOILER loss gross supply to engine

radiation steam pipes radiation from

economizer radiation from from boiler 1700 FIRE GRATE FEED CONDENSER PUMP

ACTUAL STEAM PLANT

WORK effective work ENGINE ECONOMIZER STEAM PIPE BOILER flue loss

FIRE GRATE FEED return from hotwell CONDENSER PUMP

IDEALIZED STEAM PLANT

55.SANKEY DIAGRAM OF AN EARLY STEAM ENGINE

74 One estimate places the total net virtual water water virtual net total the places estimate One picture. consumption the into incorporated be also must production industrial from as well as livestock, and crops from of food importing the with associated water virtual including demand water total taps, national of the representation internal of the Outside catchment. water local the within especially supply water on Singapore’s impact consequential a has therefore which environment, sustainable and ecosystem abalanced ensuring in critical are yet diagram of this scope the beyond are uses land of these Many reservoirs. and parks reserves, nature airport, and port for defence, national as such uses national for other land to allocate has also city-state Therefore, the hinterland. anatural without island aland-scarce is Singapore to note that important it is 36.9%, about up only development taking industrial and commercial for residential, area land the with all, After of analysis. object an as of Singapore nature state city the reflect also water. proportions These 56. Local Catchment Desalination Natural Gas Natural Petroleum NEWater Imported Products Other Coal SINGAPORE’S ELECTRICITY,WATERANDLANDUSEBYSECTORS(2017) Electricity Electricity Water (SGD) (SGD) Sales Sales Sales Transport/Other: $277m Transport/Other: Unaccounted: $39m Residential: $355m $210-220m Commercial: $210-220m Industrial: Residential: $1.55b Commercial: $1.88b Industrial: $1.82b 75 things. of scheme international broader the within a strategy such pursuing in trade-offs one of the illustrates also It importance. of strategic and localized both is sector domestic the in sustainability water to reach effort Singapore’s to which extent the illustrate also figures these Nevertheless, of production. value added higher much with and sectors service and industrial of the favor earlier, in 1980s described the in production food to move local away from of ajustification component. food basic or the crops, and by livestock island the on consumed being equivalent importation water virtual net of the percent 0.03 only with products industrial and industry in again is bulk the this Of volume. water virtual the including total grand the of proportion small year, per meters arelatively cubic 766.8 day, million per or roughly gallons 430 million of around island the within to ademand compares 1987 from This to aperiod 2001. across and year per at 11,781 of water meters cubic figure import million 43 This might also seem to be something something to be seem also might This Community Buildings, Schools, Healthcare, Healthcare, Schools, Buildings, Community Apartments, Condominiums, HDBs Condominiums, Apartments, Recreation, Places of Worship of Places Recreation, Industrial + Utilities Civic +Institutional Proportion of Land Use Use ofLand Proportion Factories, Refineries 14.1% ~10200ha 14.1% 13.8% ~9900ha ~9900ha 13.8% 7.2% ~5200ha Commercial 1.8% ~1300ha 1.8% Residential Offices, Hotels Offices, (%, Hectares)

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY e. SUSTAINABILITY, DEPENDENCIES AND VULNERABILITIES

Despite the time-bounded agreements for water moving forward will incorporate a different supply from Malaysia, Singapore continues to proportion in the mix of tap supplies than today. In strive to achieve water sustainability by 2061. This fact, judging from some projections the degree of is the case under the scenario of a doubling of reuse will shift upward appreciably from 44 percent expected water demand from the present to 2061, or so at present to around 72 percent in 2061. or from 430 million gallons per day to 860 million However, this seems able to be accomplished under gallons. Indeed, further downward movement the reference designs for NEWater and desalination on the sensitivity of factors driving demand such plant operations in the future, including likely as water conservation per capita by five to seven technical improvements. The inclusion of virtual percent, and island population by 20 percent and water requirements, nevertheless, alters the rosy predominantly among non-residents, could lessen picture appreciably with an estimated 11,781 the overall demand to 640 million gallons per million cubic meters per year of virtual water day and within projected downward shifts in the added to the current 767 million cubic meters per proportion of domestic water use to 30 percent year of island water demand. by 2061, domestic demand by households would remain at current levels of around 194 million Major among the dependencies of water with gallons per day.44 Any water supply scenario other sources and stocks of supply are energy

70% 30% 55% 45% non- domestic non- domestic domestic 258 mgd domestic 193.5 mgd 602 mgd 236.5 mgd

2015 2061 Current water demand Future water demand 430 mgd 860 mgd

76 regard to energy use and land conservation. land and use to energy regard with both direction opposite the work in System Tunnel Deep the Sewage as such advancements, technical piece-meal fact, In case. the to be However, not appear does uses. far, so value this higher- with competition of needless issue an one presents facility such that argued be it might island asmall On pollution. water and of air form the in production of this of disposal residuals any as well as facilities, production and refining for storage, necessary base land is trade-off major the supplies energy of local abundance overall. meter cubic per 0.95 kwh 0.75 of meter and water cubic to per of 1.8 kwh range the in water reused treated puts techniques newer electrodialysis-electroionisation with processes osmosis reverse energy-consumptive of highly replacement The newer technologies. so, with but not alarmingly practice, current above slightly to levels abated has treatment, water of non-conventional days early the during issue areal seemingly though demand, Energy demand. water of virtual case the in products industrial as well as food, and population use, 57. SINGAPORE’S WATERDEMANDANDSUPPLYSTRATEGY,20152030 Water demand 175L/CAPITA HOUSEHOLD 1994 45 Without any any Without Water demand Desalination 151L/CAPITA HOUSEHOLD 25% 2015 77 NEWater by 2030 to be on the order of 45 percent, and has has order of 45 and on to the be percent, by 2030 estimated is of non-residentproportion population likely Monaco. The behind density, just in state sovereign second the kilometer, is square per persons 8,041 around with Singapore, Currently land. and energy, water like of resources supplies basic and congestion development, housing, by of way physical city-state of the welfare on the placed strains other of because of Singapore non-residents in particularly in-migration of this some containment be also might outcome, however, Another well-being. material not if welfare, of social levels order to maintain in for in-migration need continued the be upshot will 2030. before of age 65 years to exceed expected people 900,000 afurther with at across-roads, is boomers’ of ‘baby especially population, aging the Furthermore, 1.2. at only standing today TFR with reached been never has (TFR) Rate Fertility for hoped 2.1 Total the as year, particularly each new citizens to 25,000 15,000 around require will policy growth espoused and overall of the Continuation or inhabitants. so now at 5.7 million standing annum, per percent to 2.5 2.0 at around advancing been has Singapore in growth Population 40% Desalina- tion 30% Water demand 130L/CAPITA HOUSEHOLD 2030 NEWater 50% 46 One One

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY been on the rise as shown in the accompanying in comparison to other world cities. New York, for table. This is also alarming to some. Indeed, some instance, though far more numerous in population slowing down in population may serve Singapore is also considerably more intense. For Singapore well among other forms of growth and generally fit a to improve and to offset potential negative trends broad model of striving for quantity at first, followed involved in moving away from growth policies, by higher consideration not just of numbers, but the will require higher efficiencies, innovation, and quality of added contributions. As indicated earlier, potential automation. It may also require rescaling reduction in the role of population growth alone of aspects of essential services, much like the Deep accrues benefits to the water supply and demand Tunnel Sewage System has for treated and reused perspective. water. Simply in terms of competing uses on a small land base, limits to technical supplies and To be sure in this ‘green-blue’ story of Singapore deliveries, and the like, there are limits to continued and in its development more generally, tradeoffs growth. Moreover, as a persistent and widening have been made, either consciously or not, destination for a particular band of services, modes among the economic, social and environmental of consumption and leisure, there seems to be the interdependencies that constitute and, in fact, very real potential of falling into what might be describe and define the island state. As noted earlier, described as a ‘high-to-mid-level trap’, where further Singapore is not renowned for any particular brand significant advancement is limited. Such an outcome, of goods although it is a popular destination for however, may not be such a bad thing, but it is one business, consumption and tourism. It has a highly in which the very strong and profound influence qualified work force and society, but its economic of water sustainability and the environment on the intensity is moderate to high, although not very high national narrative have come into play.

NET VIRTUAL WATER IMPORT TOTAL PER CAPITA (1997–2001) (104 M3/YEAR) (L/P/DAY)

CROP PRODUCTS 2,386 1,634

LIVESTOCK PRODUCTS 1,461 1,000

MEDICAL PRODUCTS 7,934 5,435

TOTAL 11,781 8,069

58.SINGAPORE’S VIRTUAL WATER USE

A related potential vulnerability is in the domain and rice, can be distinguished from livestock, of virtual water consumption and what it implies including chickens, pork and eggs in Singapore’s by way of other dependencies, although responsible case. As it turns out Singapore imports a substantial consumption is probably more apt here as a basic amount of wheat from Australia which uses two concept. With regard to food, crops such as wheat times more water on average than another source

78 high in virtual water content and cotton, used in in used content cotton, water and virtual in high relatively are Singapore, into imported mostly materials, 10 to 151 Construction US$. per liters from countries for other abroad range and US$ per liters at 50 Netherlands the and to Germany compared US$, per liters at100 for instance, States, United the content water with of virtual levels different have partners trading different average, at 7,934 year, of per water meters on cubic million content water of virtual consumer largest the far Europe. of that one about tenth is that of eggs a consumption with although imported, pork being and chicken of amounts substantial arole here with plays diet Also meters. cubic million to 2,386 compared year of per water meters cubic at 1,461 million for crops, lower than significantly is for livestock India. and China non-exporting than production of crop unit per productive less it is although high, content also is water virtual the where Thailand from purchased also is Singapore in rice Most States. United the like

With regard to industrial products, by products, to industrial regard With 47 Total virtual water consumption consumption water Total virtual 79 various nations for foodstuffs and products. products. and for foodstuffs nations various with agreements trading in consideration into content water virtual to introduce is strategy broad Asecond agriculture. of vertical forms land-consumptive some less given impossible, low, to not be seems although self-sufficiency of pursuit further of successful likelihood the Singapore, in agriculture high-tech to pursue of attempts failure the Given noted. as eggs, and pork chicken, in self-sufficient was nation the that to Prior anything. much as as Singapore green’ and a‘clean order to pursue 1980s in the broken in off was earlier, this narrated As self-sufficiency. food of levels high to achieve striving be would first water. The of virtual consumption responsible towards taken be can that approaches two are there general In high. extraordinarily is clothing, a later chapter. later a in with dealt be will However these perturbations. weather other and rise level sea change, climate to come from seen be also may picture blue-green to Singapore’s threats existential other Some

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY endnotes

1. Oon, C. 2009. Key step to water adequacy. Straits Times, June 13. Based on assumption of author in Lenouvel, p.789. 24 14. Lenouvel et al., p.789. 2. Lenouvel, Vincent; Michel Lafforgue; Catherine Chevauche and Pauline Rhétoré. 2014. “the energy cost of water 15. Microfiltration is a type of physical filtration process where independence: the case of Singapore” Water Science and a contaminated fluid is passed through a special pore-sized Technology: a journal of the International Association on Water membrane to separate micro-organisms and suspended Pollution Resources. 70:5, p.789. particles from process liquid.

3. Lenouvel et al., p.789. 16. PUB, “Innovation in Water Singapore”, June 2011, https:// www.pub.gov.sg/Documents/InnovationWater_vol1.pdf 4. Interview with Mr. Harry Seah, Director of Technology of PUB on 6 February 2017. 17. Water: From Scarce Resource to National Asset, Urban Systems Studies Booklet Series. Singapore: Cengage 5. Tan, Irene. 2016. Beyond Singapore’s blue-green matrix: an Learning Asia, 2012. international comparison of blue-green systems in Melbourne and Singapore (Unpublished paper, 14 July). 18. Lenouvel et al., p.786f.

6. The Public Utilities Board was set up as a statutory board 19. Lenouvel et al., 2013, p789. in 1963 to provide electricity, piped gas and water supply for Singapore. In 2001, the electricity and gas undertakings 20. Vanham, P.269. of the Public Utilities Board were transferred to a newly set up statutory board called the Energy Market Authority. 21. Lenouvel et al., 2014. The Public Utilities Board was then reconstituted as the national water agency, known officially as PUB, Singapore’s 22. PUB, 2016. National Water Agency. The idea was for PUB to manage Singapore’s water supply, water catchment and used water in 23. Vanham, p.289. an integrated and more holistic manner. 24. Seah, Harry; K. L. Khoo; J. Y. Chua;mD. Toh and S. C. Based on an interview with Mr. Tan Gee Paw, Chairman, Chua. 2010.”Cost effective way to harvest estuarine water: PUB on 9 February 2017 and Channel News Asia. “PUB to variable salinity desalination concept” Aqua – Journal of expand groundwater monitoring network” (26 May 2016, Water Supply: Research and Technology 59:6-7, pp.453-454. 11:23 am). 25. Seah, p.458. 7. Lenouvel et al., p.789. 26. Machuca, Lubomir and Vit Fara. 2014, “Combination of 8. Lenouvel et al., p.787. Electrodialysis and Electrodeionization for Treatment of Condensate from Ammonium Nitrate Production.” World 9. Allan, J. A. 1998 (2005) “Virtual Water: A Strategic Academy of Science, Engineering and Technology International Resource, Global Solutions to Regional Deficits”. Journal of Energy and Power Engineering, vol 8, no 6, pp. Groundwater. December, pp. 545-546. 485-487.

10. Hoekstra, A. Y. and A. K. Chapagain. 2007. “Water 27. Siemens. 2017. Ingenuity for Life: Our History in Singapore. Footprints of Nations: water use by people as a function of https://www.siemens.com/ and “Siemens to develop their consumption patterns”. Water Resources Management innovative sea water desalination technology” (Monday, 21:1, pp. 35-48. June 23, 2008).

11. Vanham, D. 2011. “How much water do we really use? A 28. Based on an interview with Ms. Olivia Lum, Founder of case study of the city-state of Singapore. Water Science and Hyflux on 15 August 2017. Technology-Water Supply. 11:2, p.234. 29. Public Utilities Board. 2016. Our Water, Our Future. 12. Lenouvel et al., 2013, p789. (Singapore: Public Utilities Board).

80 42. 41. 40. 39. 38. 37. 36. 35. 34. 33. 32. 31. 30.

have used the assumption that no residential households households noresidential that assumption the used have we Here, regimes. different to subscribed sector each of shares different with rates, electricity non-contestable and contestable both are there reality, in For electricity, standards. byglobal lass of low rate extremely an reflects system the in for unaccounted 5% water of The $39 million. around worth be might it sold, be to were water that if so system, the throughout spread equally is losses) other or flushing leaks, include may (which water unaccounted-for that We assume $785 million. around total sales Annual negligible. as non-zero, though ships, resupplying for sold water treat we recommendation, PUB’s on Based categories. two these for prices water non-domestic and We domestic used users. commercial and industrial among split is remainder the and for; unaccounted is water of 5% households; to sold be to estimated is 43% water of Science). Social Integrated 1861 March, Napoleon’s 2001. John. Corbett, History” 1: Part Management, Flow Material and Energy in Diagram Sankey “The 2008. Mario. Schmidt, see, Also Diagram. Diagrams”,https://en.wikipedia.org/wiki/Sankey_“Sankey (p22). 2011 Vanham, p, 222. Vanham, on based paragraph the of Remainder wastewater-recycling. article/drinking-toilet-water-science-and-psychology- https://www.earthmagazine.org/ at Available [online]. recycling. wastewater of psychology) (and science The water: toilet Drinking S. Lemonick, tables. accompanying in data See Mr. Hin. with Interview 2017. June 22 on PUB, Department, System Tunnel Sewerage Deep the of Mr. Yong Wei Director with Hin, interview an on Based p.792. al., et Lenouvel p.452-458. Seah, 6Feb 2017. Seah, Mr. Harry with Interview 2017. 16 on PUB August Networks, 3P Director, Deputy Mello, De Linda Ms. with Interview Journal of Industrial Ecology Industrial of Journal Charles Joseph Minard: Mapping Mapping Minard: Joseph Charles .(Washington, DC: Centre for Spatially Spatially for Centre DC: .(Washington,

12:1, pp. 82-94. pp. 12:1, Earth Magazine Earth , 81 45. 44. 43. 47. 46.

sg/DATA/0/docs/NewsFiles/Energy%20efficient%20 http://www.e2singapore.gov. at Available Singapore. in desalination seawater efficient Energy n.d. Asia, H2PC 2016. PUB. (2016). PUB and (2007) Chapagain and (2011), (1998), Vanham on Hoekstra Allan Based future. the in outcomes pricing new yield also will which market, electricity open an be will Singapore of 2017. 2018, of end all the By of months twelve the on based is data electricity Our (USEP). Price Energy Singapore Uniform on based price asimplified on relies expenditures contestable for Estimates pricing. contestable use commercial and industrial of majority the but rates, electricity conetstable to subscribe from the copyright holder. copyright the from directly permission obtain to need will you use, permitted the exceeds or regulation statutory by permitted not is use intended your and license Commons Creative chapter’s the in included not is material If material. the to line acredit in otherwise indicated unless license, Commons Creative chapter’s the in included are chapter this in material party third other or images The made. were changes if indicate and license Commons Creative the to alink provide source, the and author(s) original the to credit appropriate give you as long as format, or medium any in reproduction and distribution adaptation, sharing, creativecommons.org/licenses/by/4.0/), which permits use, (http:// License International 4.0 Attribution Commons Creative the of terms the under licensed is chapter This Access Open p.45f. and p.227 Vanham, on partially based Paragraph 2017. Singapore, Statistics of Department See desalination.pdf Our Water,Our Future Our

. (Singapore: PUB). (Singapore: . Population Trends ,

CHAPTER 4 WATER RESOURCES AND SUSTAINABILITY