1.1. Early Water supply source to Chennai (Madras):
- Till about 1870, the people of Chennai (Madras) were dependent on shallow wells situated in their own houses or on public wells and tanks in the neighbourhood for their water supply needs. There was no protected water supply at that time and these sources were not satisfactory.
1.2. Development of organised water supply system:
- The organised water supply to Chennai was commenced in 1872 which is the nucleus of the protected surface water supply system now in existence in Chennai City. A masonry Anicut (weir) of 1.8 m height was constructed, across the Kosathalaiyar River at Tamaraipakkam about 28 km. north-west of Chennai. The unfiltered water from this Anicut was brought to Kilpauk through Redhills Lake by an open channel by gravity and distributed through Cast Iron (CI) pipes to the nearby areas. This initial gravity system consisted of Tamaraipakkam Anicut, Upper Supply Channel of 13 km. length to convey the diverted water from the Anicut to Cholavaram Tank, Lower Supply Channel of 4 km. length to convey water from Cholavaram to Redhills Lake, an open channel of 11 km. length to convey water from Redhills Lake to masonry Shaft at Kilpauk and cast iron mains to distribute the unfiltered water to the city.
1.3. Beginning of protected water supply system:
- The first major milestone towards protected water supply using of filtration and pumping was achieved during the year 1914. An improved intake tower, named as Jones Tower, was constructed in 1881 at the deepest point in the Redhills Lake. An underground masonry conduit of size 1.52m x 1.12m and 11 km. long was constructed to convey raw water from Redhills to Kilpauk, in the place of the open earthern channel, with conveying capacity of raw water at the rate of 104 MLD (23 MGD). Slow sand filters to purify the water (60 to 70 MLD), four underground pure water storage tanks (29.50 ML capacity), steam engine driven pumps, an elevated steel overhead tank (6.75 ML capacity) and 48" dia steel pumping main from Kilpauk Pumping Station to Shaft were installed. Subsequently the distribution system was remodelled and extended to all areas of the city.
1.4. Development of new sources:
- Poondi Reservoir (later named as Sathyamoorthy Sagar) was constructed in 1944 across the Kosathalaiyar River with a capacity of 2573 Mcft and placed in service for intercepting and storing Kosathalaiyar River water. Surplus water flows down the river which is again intercepted by Tamaraipakkam Anicut and diverted to Cholavaram Lake. (A lined canal known as Poondi Canal was later constructed in 1972 to convey water from Poondi Reservoir to Cholavaram Lake). The combined storage of three lakes viz. Poondi, Cholavaram and Redhills was 5596 Mcft (Poondi: 2573 + Cholavaram: 583 Redhills: 2440). The system was then designed for a supply of 115 lpcd for an estimated population of 0.66 million expected in 1961.
1.5. Improvement works carried out during 1946 to 1966:
- To meet the immediate needs, various works for conveyance, treatment and distribution were carried out between 1946 and 1966. Rapid gravity sand filter treatment facilities with 45 MLD capacity were completed in 1959. Construction of a second underground masonry conduit (size 1.98m x 1.22m) to convey additional quantity of 146 MLD of raw water (32 Million Gallon per day) from Redhills to Kilpauk, installations of Electrical pumping units at Kilpauk replacing the 3 steam engine driven pumpsets, second 48" pumping main from Kilpauk Pumping Station to Shaft, 42" Trunk Main to serve South Chennai, 2 additional underground filtered water tanks of 9 ML capacity (2 Million Gallons) each at Kilpauk and expansion and improvement to distribution system are important works carried out.
1.6. Source Augmentation works:
- Simultaneously, action was taken to augment the sources and improve the treatment and storage facilities. The construction of a lined channel from Poondi to Tamaraipakkam for a length of 15 km. to convey water from Poondi to Tamaraipakkam was completed in 1972 to reduce the transmission loss. The combined capacities of Cholavaram and Redhills lakes were increased by 700 Mcft by raising the lake bunds. Thus, the combined storage capacity of Poondi, Cholavaram and Redhills was increased to 6296 Mcft (Poondi: 2573 + Cholavaram: 881 + Redhills: 2842). The irrigation rights of Cholavaram lake and Redhills lake were acquired in 1962 and the entire storage was made available for the City supply.
1.7. Additional works carried out during 1968 to 1978:
- Additional 135 MLD capacity Rapid sand filter treatment facility was commissioned in 1969 at Kilpauk. A prestressed concrete overhead tank of 6.8 million litres capacity and the 7th underground clear water storage tank with 10 million litre capacity was constructed at Kilpauk Water Works. The city distribution system was divided into 12 zones, each zone to feed by a separate trunk main radially from Kilpauk Water Distribution Station. During 1962, a separate water distribution station was constructed at Anna Poonga to serve the northern portion of the city and at Thiyagaraya Nagar, the Southern Head Works during 1973 to serve the southern zones. The existing Kilpauk Water Distribution Station was serving the central portion of the ctiy.
1.8. Abstraction of Ground water:
- Based on the UNDP studies carried out during 1966 to 1969, ground water aquifer was identified at Tamaraipakkam, Panjetty and Minjur in the Araniar-Kosathalaiyar Basin (A.K. Basin) located north of Chennai. These three Well fields were developed for abstracting water at an estimated yield of 125 MLD. Ground water abstracted through bore wells from these well fields was supplied to Industries in Manali from 1969 by the PWD Ground Water Wing, later on, after taking over by CMWSSB in 1978, this water was partly diverted to City's water supply system from 1981.
2.1. To augment water supply to Chennai with consequential improvement and expansion of the existing water distribution system, a Master Plan was formulated in 1978. This Master Plan identified river Krishna as one of the viable sources for the Chennai Metropolitan Area. CMWSSB implemented the improvement works in a limited way till 1991 depending upon the funds availability.
- The following are the important works executed:-
- a. Construction of 8th underground clear water storage tank of 10 ML capacity at Kilpauk.
- b. Renewal of old and choked up water mains for a length of 43 km.
- c. Development of new water distribution zone (13th zone) with 34 km. long pipeline network.
- d. Construction of third masonry conduit of size 2.13m x 1.37m with a conveying capacity of 190 MLD for a length of 11 km. completed in 1986.
- e. Kalaignar Karunanithi Nagar Water Distribution Station (K.K. Nagar).
- f. The K.K. Nagar Water Treatment Plant was constructed by TNHB during the year 1970 with a treatment capacity of 4.5 MLD (1 MGD). The source of water supply was from 4 Nos. of infiltration wells at Porur Lake and 5 Nos. of infiltration wells at Virugambakkam Lake. Water from these infiltration wells has been conveyed through 450mm dia A.C. pipes by gravity and supplied to K.K. Nagar after necessary treatment. This system was taken over by CMWSS Board in the year 1978. Till 1992, water supply to K.K. Nagar has been made from the above said sources. After failure of infiltration wells at Porur and Virugambakkam, the water from Porur Lake alone at 2.7 MLD is drawn, treated at K.K. Nagar water treatment plant and distributed in addition to the supply received from Redhills/Veeranam sources to the locations such as K.K. Nagar East & West, Ashok Nagar, MGR Nagar East & West, West Mambalam (part), Nesapakkam and Jai Balaji Nagar.
- g. Distribution system provided to unserved areas for a length of 70 km.
- h. The 12 Panchayats around the periphery of the city i.e. Kodungaiyur, Vyasarpadi, Erukkanchery, Kolathur, Villivakkam, Thirumangalam, Virugambakkam, Saligramam, K.K. Nagar, Velachery, Tharamani and Thiruvanmiyur were added to City limits in 1978 and CMWSSB took action to provide water supply and sewerage services to these areas.
- i. Southern Coastal Aquifer was developed along the coast of Bay of Bengal during 1973-74 and extended for about 20 km. between Thiruvanmiyur and Muttukad during the year 1975-77 by TWAD Board. This was taken over by CMWSSB in June 1984. The safe yield of this aquifer is 10 MLD and supplied to part of Thiruvanmiyur area, TNSCB tenements at Okkium Thuraipakkam and Aavin at Sholinganallur. However, in order to avoid sea water intrusion due to depletion in water level, the present drawal has been restricted to only 1.5 MLD.
- j. During 1982 to 1985, an UNDP/UNTACD Aided Hydrogeological and Artificial Recharge studies were carried out which identified the potential for developing three additional well fields (Poondi, Kosathalaiyar Flood Plains and Kannigaiper) to abstract about 55 million litres per day of ground water in A.K. Basin and transfer of flood water from Araniar river to Kosathalaiyar river to realise 27 MLD of water. These two schemes were completed under First Chennai World Bank Aided Project in 1987.
- k. From the three surface sources (Poondi, Cholavaram and Redhills) and 6 ground water well fields (Minjur, Panjetty, Tamaraipakkam, Poondi, Flood Plains and Kannigaiper), about 318 MLD of water was abstracted of which 273 MLD was supplied to Chennai City at an average of 70 lpcd and 45 MLD supplied to Industries in Manali area till September 28, 1996. Water distribution to the city from the 4 Head works viz. Kilpauk, Anna Poonga, Southern Head Works & K.K. Nagar through the radial zonal trunk main/distribution mains were continued.
2.2. Construction of 90 MLD Treatment lant:
In order to supplement the mechanical treatment capacity at Kilpauk Water Works, an additional module of 90 MLD capacity was sanctioned by the Government for Rs.295 lakhs in the year 1983. The works of construction of Filter House, Clarifiers, Chemical House and 9th filtered water underground tank were completed and commissioned on 14th April 1990. With this additional capacity, the total treatment capacity by Mechanical Filters increased to 270 MLD at Kilpauk which helped to treat the water at uniform standards before distribution.
3.1. An agreement was signed jointly by Governments of Maharashtra, Karnataka and Andhra Pradesh on April 14, 1976 to spare 15 thousand million cubic feet (TMC) of Krishna water to Chennai city. Following this, an accord between Andhra Pradesh Government and Tamil Nadu Government was signed on April 18, 1983 for drawing 15 TMC of Krishna water to Chennai City from Sri Sailam Reservoir to be conveyed through Somaseela and Kandaleru Reservoirs and ultimately a net quantity of 12 TMC (after loss of 3 TMC enroute in evaporation and seepage) will reach the Tamil Nadu border.
3.2. Initial works for supplying water under this scheme were completed in 1996 and from September 1996, water is received at Poondi Reservoir from Kandaleru Reservoir in Andhra Pradesh through 152 km. long open canal upto Tamil Nadu Border near Uthukottai. Then, the water is conveyed through 25 km. long open canal to Poondi Reservoir. From Poondi Reservoir, water is transferred to Redhills and Chembarambakkam Lakes through Link/Feeder canals and supplied to city after treatment.
4.1. The Master Plan for water supply to Chennai formulated in 1978, was subsequently updated in 1991 on the following basis:-
- i. Water supply to be augmented by a quantity of 930 MLD from Krishna River.
- ii. Water demand for projected population in 2021 and apportion the available quantity among the beneficiaries.
- iii. To design the system components and install progressively, step by step, with augmentable quantity so that allocated water could be supplied with facility to reinforce the system to distribute 2021 water demand if additional sources could be identified.
- iv. The Master Plan to be implemented in two stages. In Stage I, infrastructure requirements for supply of 400 MLD of Krishna water would be created. In Stage II, infrastructures would be strengthened and expanded to supply additional 530 MLD of Krishna water.
- The First stage Master Plan was taken up for implementation in phases using available sources of funds and also under World Bank Aided First Chennai Water Supply and Sanitation Project. This Project was implemented from Dec. 1987 to March 1996. New Well Fields (Poondi, Kosathalaiyar Flood Plains and Kannigaiper) to extract additional 55 MLD of water from AK Basin was developed in 1987. Construction of 300 MLD capacity water treatment plant at Redhills was completed and commissioned in 1996. The transmission mains were laid from the treatment plant to North Chennai, Central Chennai and South Chennai for conveying treated water to City Distribution Station. Also, old and choked up distribution mains were renewed.
4.2. Increase in the storage capacity of the Lakes:
The Public Works Department executed the works for increasing the storage capacity of the Poondi, Redhills and Chembarambakkam Lakes under the Krishna Water Supply Project during 1991-92.
The present capacity of the Lakes is as follows:
|Lake||Capacity (In Mcft.)|
5.1. The Master Plan updated in 1991 was revised in August 1997 based on the updated water requirement and water allocation for each beneficiary as per the actual census figure of 1991. The updated (1996-97) water requirement and water allocation for each beneficiary were assessed as follows:
|Area||Water requirement (in MLD)||Water allocation (in MLD)|
|2001||2021||Krishna Stage I||Krishna Stage II|
|1. Chennai City||710||942||525||760|
|2. Spl. Industries in Manali||170||330||140||300|
|3. Adjacent Urbanised Areas||333||511||130||228|
|4. Distant Urbanised Areas||114||197||32*||69|
* From Local Sources
5.2. As per the Revised Master Plan proposals, Chennai City water distribution system has been divided into 16 Zones. For this, 12 Water distribution stations were newly constructed and improvements to the 11 water distribution systems were completed. Leak detection and rectification works were carried out as water conservation measures by replacing the old and choked up water mains for a length of about 585 km. and 1.95 lakh house service connections were renewed. Transmission mains for a length of 36 km. were laid to convey water to various water distribution stations. The Kilpauk water treatment plant has been refurbished for treating 270 million litres of water daily. Also, bulk meters were fixed in the water treatment plants and water distribution stations.
Geographical Information System (GIS) was developed in a pilot area. Information System Technology Planning (ISTP) was implemented as a pilot project. A detailed study on the potential of Araniar-Kosathalaiyar River Basin for the extraction of ground water has been carried out during 2002-2004 and assessed that 100 mcm per year during normal years and 70 mcm per year during drought years can be extracted from these aquifers. These 16 Water Distribution Zones are provided with a separate water distribution station which is fed by a dedicated transmission main from the treatment plant.
The Veeranam Water Supply Project was implemented as additional source of water to Chennai City. The Project was commissioned in the year 2004 to supply 180 MLD of water to Chennai City by drawing water from Veeranam Lake. This lake receives water from Cauvery River system through Kollidam, Lower Anicut and Vadavar Canal besides rainwater from its own catchment area. The capacity of the lake is 1465 Mcft. The lake water is treated at Vadakuthu Water Treatment Plant by pumping raw water at a distance of 20 km. from Sethiathope to Vadakuthu through 1775 mm dia mild steel pipe. The treated water is then pumped at a distance of 8 km. to Break Pressure Tank at Kadampuliyur through 1750 mm dia mild steel pipe and from there the water is conveyed to a distance of about 200 km. through the mild steel pipe of 1875 mm and 1500 mm dia by gravity to Porur Water Distribution Station near Chennai. From this Distribution Station, water is distributed to Chennai City through Trunk mains and Water Distribution Stations.
Metrowater also purchased water from the private agricultural wells in the Araniar-Kosathalaiyar Basin to augment the source. The water from the private agricultural wells conveyed through the Well Fields pipeline network to the Chennai City and other consumers. Till Jan 2008. During poor storage in the lakes, the water from these wells may be drawn based on the boards requirements.
To treat the water received from Krishna water source under the Telugu Ganga Project, construction of a 530 MLD water treatment plant at Chembarambakkam near Chennai and transmission line was sanctioned by the Government during August 1996 with an estimated cost of Rs.296.00 crore. Now, the construction of the Plant has been completed by the CMWSS Board. The trial operation of the plant began on 8.4.2007. The plant has been inaugurated on 19.7.2007.
The surapet water treatment plant of 14 mld capacity was taken over from TWAD Board from 01.08.2009 for further Operation and maintenance.
A Desalination plant of 100mld capacity has been commissioned on 31.07.2010 at Kattupalli Village near Minjur. The plant was constructed by DBOOT (Design, Build, Own, Operate & transfer) basis by M/s. Chennai Water Desalination ltd (CWDL) and metro water has entered bulk water purchase arrangements with the firm for 25 years.
Presently the total water treatment capacity for Chennai City is as follows:
|Water Treatment Plant||Capacity (In MLD)|
|Vadakuthu (Veeranam Lake Source) (2004)||180|
|Minjur Desalination Plant||100|
|Nemmeli Desalination Plant||100|
The following is the growth profile in water supply since the formation of the Board in 1978 to July 2018.
|Operational Area||City 176 sq.km.||426 sq.|
|Population||30 Lakh||74.38 Lakh|
|Water produced (Normal years)||240 MLD||830 MLD|
|Area covered with piped supply||80%||99%|
|Treatment capacity||182 MLD||1,494 MLD|
|Length of water mains||1,250 km.||6,697 km.|
|No. of consumers||1,16,000||8,76,891|
|Majore Distribution Stations||3 No.||16 Nos.|