Introduction Mumbai, is one of its 10 mega cities of the world and business capital of India. Mumbai proper occupies a low-lying area that once consisted of seven islands called Colaba, Mazagaon, Old Woman's Island, Wadala, Mahim, Parel, and Matunga-Sion separated from each other only during high tide. The population has risen from merely 3 millions in 1951 to 12 millions as on 2002 out of which 50 % live in slums It also supports “daily commuting” population of 20 lakhs It covers an area of 437 sq.km. With average density of 36600 soul/ sq.km. Water Supply-From Past To Present Prior to 1870, the Mumbaikar used to drink water from the existing well, lakes and tanks. But during middle of nineteenth century, because of the epidemic, decision was taken to build a dam to supply good quality of potable water, and then onwards Bombay water works started functioning The history of Mumbai’s water supply dates back to the 22nd June 1845. On this day, the then Government in response to the agitation of the native appointed 2 men Commission to report about the quality and quantity of water available in Mumbai. The Commission reported back within 24 hours that the water supply of Mumbai needed immediate attention. This was the beginning of efforts to search sources of water to satisfy the City’s demand. It is the first city in India to receive piped water supply in the year 1860. Today it supplies 2950 MLD every day, is one of the largest water supply in Asia. Sources of Supplies are four lakes namely Tansa, Vaitarna, Vehar and Tulsi. about 110 km from Mumbai.The water is treated in two plants namely Panjarapur & Bhandup and stored at two Master Balancing Reservoirs namely Yewai & Bhandup with 1910 MLD ,the largest water treatment plant in Asia and further supplied to the city through 26 service reservoirs. The entire network is spread over an area of 430 sq km, while the sources are 40 to 60 kms away from the Master Center. WATER SUPPLY TO GREATER MUMBAI SNO Source of water supply Daily supply in mld Year since it commissioned 1 Vihar lake 67 1860 2 Tulsi lake 18 1879 3 Powai lake 4 1891 4 Tansa river scheme 494 1948 5 Vaitarna- cum-Tansa scheme 490 1957 6 Ulhas river scheme 90 1967 7 Upper Ulhas scheme 550 1972-73 Source : CGWB manual on groundwater in urban environment of India How Much Is Supplied? The Brihanmumbai Municipal Corporation is responsible for providing water supply, managing and operating the network and billing and collecting revenues to the population of Greater Mumbai ( more than 12 million people). The department in charge of these functions is the Hydraulic Engineer’s department. There are around 300,000 water connections in Mumbai. Most of the supply is for domestic purposes ( 85 %). The non-domestic demand ( 15 %) has been decreasing over the years in parallel with the decline of water consuming industries ( mostly textile and dairies).The Municipal Corporation of Greater Mumbai presently supplies water at 135 LPCD to the consumers in planned development, which is recently curtailed to 90 LPCD because of rapid rate of development, constant influx in the city and no augmentation in water supply in near future. City today needs nearly 4000MLD of water. With an Status of water supply in Mumbai expected population growth of 2% per year, the 3800 projected water demand in 2011 will be 4500MLD. 4000 Water is supplied at the rate of 2980 MLD from 2950 3000 surface water. Average supply is around 240 to 250 2000 lpcd. However large discrepancies exist according to the type of settlement and the type of connections. 1000 Surface water provided to the city by a gravity system 0 is the main characteristic of the supply of Mumbai Million litres per day DEMAND SUPPLY where groundwater plays no role. Water is supplied on source: Braham Mumbai Corporation a rotational basis among the 107 distribution zones because of the reservoirs capacity. Intermittent supply is the rule in Mumbai and supply can vary from two to six hours. Who Needs How Much? WATER REQUIREMENT OF GREATER MUMBAI(1991,2001,2011) 5000 4525 3819 3529 4000 3080 2823 2521 3000 2200 2017 2000 1489 400 400 400 1000 38 54 69 90 90 90 0 Domestic Industrial Other uses Enroute Total (net) Total ( gross) Water Requirement(in MLD) institutional Type of Use Note : The projected demand of water for Greater Mumbai for the year 2021 is estimated to be 5355 mld. Source : CGWB manual on groundwater in urban environment of India SITUATION ANALYSIS Out of the gross water supply of 3,193 MLD, after accounting for leakages, the net availability amounts to 2,320 MLD. This includes 600 MLD water supply for non-domestic purposes, namely, industry and commerce. The water losses through leakages in water supply distribution system amount to almost 25%. This is very high despite the MCGM efforts to reduce the same to 15%. SOURCES OF WATER SUPPLY 700 590 550 600 494 500 400 300 200 67 90 100 18 4 Capacity(MLD) 0 Vihar Tulsi Powai Tansa Vait Ulhas Upper lake lake lake river arna- river Ulhas scheme cum- scheme scheme Tansa *Expected year of completion-Gargai-2009 & Shai-2009. * The average gross per capita water supply is 260 litres, while the net water available for domestic use is about 155 litres per capita per day (lpcd). This net availability no doubt exceeds norm of 135 lpcd set by the Bureau of Indian Standards (IS). Apparently, the water supply status appears to be satisfactory on the whole. However, the fact that there are a good number of private water suppliers and a conspicuously large market for water provides elegant testimony of inadequacies of water management in the city. * Surely, the aggregates should not give any complacency to the municipal authorities. The spatial, temporal and sectoral coverage of water is still missing i.e., some parts of the city do not receive water; some of them receive it intermittently; and some sectors have more privilege in accessing it than others. Connection Nature of Use Tariff (Rs per thousand litres) Metered: Domestic -Slums/Chawls 2.25 -High rise buildings 3.50 Commercial/Industrial 10.50 - 38 Unmetered: Domestic 65% of the rateable value Commercial/Industrial 130% of the value rateable value Source: Municipal Corporation of Greater Mumbai (2002) Moreover, the municipal norms of water supply have been fixed at 45 lpcd in slums, 90 lpcd in chawls and 135 lpcd in high rise buildings, respectively. However, the actual water supply widely varies between wards and even localities within a ward. For example, it varies from 50 lpcd in slums to 250 lpcd in high rise buildings. What Will Be The Future Supply? FUTURE SOURCES OF WATER SUPPLY The present supply versus demand percentage satisfaction is about 76 %. Looking to the growth of city and day- by- BHATSA ( 350 MUMBAI III A) day increasing demand, there is an urgent need to identify MIDDLE and commission new sources of water supply. Govt of 865 VAITARNA Maharashtra has allotted additional 350 MLD of water 455 GARGAI from Bhatsa sources. This project is known sa Mumabai III-A project. 455 PINJAL This project has been taken up on priority basis to utilise this additional water from Bhatsa source. The estimated cost of this project is Rs 700 crore. This project is expected to be completed by the end of year 2007.The important components includes several works like raising height of Pise weir by 2m (work completed ) ,laying of 3000 mm dia main from Pise to Panjrapur (total length about 9 kms Part of the work of 3 kms is completed.),pumping station at PiseTreatment plant of 455 MLD capacity at Panjrapur, raw water pumping station of 635 MLD capacity at Panjrapur ,tunnel from Bhandup comlex to Malad Hill reservoir and further extension upto Liberty Garden and Charkop, tunnel from Veravli Hill reservoir to Oshiwara and Yari road.and laying of 3000 mm dia water main from Mulund Goregaon link road to Amar Mahal along Eastern Express Highway The future sources of water supply to Mumbai city to fulfil the requirment have been identified. The identified sources and the estimated yield from each source is Vaitarna river basin and Ulhas river basin are as under: Vaitarna River Basin 865 Water from sources in Vaitarna river basin can be 1000 brought to city by gravity. The feasibility report 455 455 500 for Middle Vaitarna project has been completed. The final technical details like type of dam, etc.is 0 being worked out. Most of the clearances required Capacity(MLD) Middle Gargai Pinjal have been obtained. However, clearance from Vaitarna Envrionmental Department of Govt. of India is yet awaited. The major components of works identified in Middle Vaitarna project includes a location of dam between Upper Vaitarna & Lower Vaitarna, tunnel of 3500 mm dia length of 8 kms from Modak Sagar ( vaitarna) to Y-branch ,a 3000 mm dia water main between Y- branch and Gundavali for a length of about 33 km in different stretches and additional treatment plant at Bhandup complex of 590 MLD capacity. For Gargai and Pinjal sources the water can be transmitted to Modak Sagar through tunnels by gravity. Further from Modak Sagar water can be easily brought to Bhandup complex with existing and additional conveyance system. It would be beneficial to tap sources from Vaitarna basing from where water can be brought by gravity upto Bhandup complex where, adequate land for accommodating additional treatment plant and to enhance the capacity of Master Balancing Reservoir – I is available at appropriate elevation.