Chennai has always been reliant on natural reservoirs such as lakes to meet its water requirements. In the past two decades, the city has suffered multiple losses due to extreme weather patterns, which led to the infamous “Day Zero” in 2019 – when reservoirs went dry and no water was available. Having witnessed such extreme situations, the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) is determined to develop diverse sources of water supply to prevent such mishaps in the future.
Recent trends and developments
The demand for water in Chennai city has risen by more than 50 per cent on account of industrial development, increasing population, and larger per capita needs fuelled by economic growth and lifestyle changes. Recent water trends have left Chennai rain-rich but water parched. It is one of the first major cities in the world to have run out of water.
In the past year, the city has witnessed significant developments in the water segment. From the setting up of new water treatment plants to the introduction of the latest technologies, the state authorities have undertaken several initiatives. They have made tremendous efforts to build resilience against water shortage in the city. One of the key initiatives is making rainwater harvesting mandatory for households and commercial buildings. This has made Chennai the first Indian city to reuse 10 per cent of its collected wastewater. The city now plans to expand this to 75 per cent.
The use of technology is being increased in the city to make 24×7 potable water available to its citizens. To this end, metro stations in the city are providing potable water to passengers out of thin air – literally. Atmospheric water generators that can convert air into drinking water have been installed at the metro stations. All 41 metro stations in the city have installed reverse osmosis technology to provide drinking water to passengers at the concourse level. Each of these atmospheric generators entailed an investment of Rs 0.6 million. They draw moisture from the humidity in the air. The moisture is then passed through a condenser, where the coils turn it into water droplets, which are then stored in a tank. The water then undergoes a four-step filtration process before it is passed to another tank. Subsequently, the water is ozonated via an ozone generator. Finally, the water is dispensed in either regular or cold form for the commuters through a dispenser. This technology is most useful for the city during water crises.
The Tamil Nadu Water Resources Department is also developing an artificial intelligence (AI)-enabled application to protect the water bodies in Tamil Nadu. This application will have satellite support as well. The first phase of this initiative will be taken up in cities such as Chennai, Kancheepuram and Tiruvallur, entailing an investment of around Rs 2.5 billion. A pilot project has also been planned to monitor the water bodies and ensure good water quality in areas in and around Chennai. The pilot will involve the prevention of encroachment on water bodies, the clearing of such encroachments, and subsequent replenishment of the water bodies.
Meanwhile, to check the water quality in Chennai and ensure the provision of clean drinking water, CMWSSB, in November 2022, inaugurated a government-owned laboratory in the Kilpauk area built at an investment of Rs 70 million. Here, citizens can check the quality of the running water from the taps in their households. An amount of Rs 75 is being charged for testing for households, and Rs 200 for commercial establishments. The laboratory can also test water from open wells and borewells at an amount of Rs 200 per sample. Moreover, it has separate facilities for testing the quality of sewage discharged from sewage treatment plants (STPs). Furthermore, it is collecting drinking water samples from around the city to test water quality on a daily basis. CMWSSB also has a Quality Assurance Wing to analyse the water resources used by the public, such as open wells and borewells.
At present, Chennai generates over 580 million litres per day (mld) of sewage, which is treated at various STPs across the city. The existing STPs have the combined capacity to treat nearly 745 mld. In order to increase the treatment capacity to about 1,000 mld by the end of 2023, CMWSSB is building new STPs at Koyambedu, Kodungaiyur, Nesapakkam and Perungudi. They will have a combined treatment capacity of around 350 mld and are expected to cater to the projected population in 2035. These new plants will comply with the norms of the Central Pollution Control Board. They will adopt new technologies such as sequential batch reactors, which require less space and produce reclaimed water of better quality.
The Greater Chennai Corporation (GCC) is also planning to set up an eco-friendly drainage system on the East Coast Road in Chennai. The drains in this new system will be made of recycled material such as melted plastic, electronic waste and rubber. Artificial wetlands, rainwater harvesting systems and sponge parks will be created to help with recharging groundwater. This system will replace the concrete box-type drainage system, and help in reducing pollution in the sea. It is also expected to increase the groundwater level. Furthermore, GCC is also exploring the feasibility of using robots for the cleaning of stormwater drains in the city. The super sucker lorry used by the authority has been able to clean only small distances of 20 to 30 metres a day. Chennai city has around 2,200 km of stormwater drainage, and so extensive technology adoption is required.
Some of the key focus areas for Chennai city include efficient use of water, reduction of non-revenue water, and equitable distribution of water to all citizens. To this end, CMWSSB is aiming to achieve 100 per cent water metering of all commercial connections by 2023 and 80 per cent of domestic connections by 2027. CMWSSB’s Metering Policy 2022 aims to promote water conservation. The city currently has very low metering facilities unlike cities such as Delhi and Bengaluru, and there is a wide variation in the hours of supply and pressure of supply. The tariffs also vary a lot in the city. The installation of meters will help give accurate figures of consumption and provide data regarding water loss, which is important for a water-scarce city such as Chennai. The meters will be installed in phases, commencing with high-revenue categories and all non-residential and commercial complexes as well as for new consumers. These meters will be owned by CMWSSB and consumers will be levied a fixed rental charge for them. In all, CMWSSB has installed 24,095 meters in the city, accounting for 3.12 per cent of the total.
CMWSSB has also started operations at the newly launched tertiary treatment ultrafiltration plant (TTUF) at Nesapakkam on a trial basis. It is discharging the reclaimed water into Porur lake, which will then be used for drinking water supply in the city. The TTUF has a maximum capacity to treat 10 mld of wastewater. Currently, it is operating at 80 per cent of its capacity. This initiative is aimed at creating a climate-resilient water supply infrastructure and promoting indirect use of reclaimed water for domestic purposes. With this pilot project, CMWSSB is trying to validate the functioning of the TTUF. The quality of recycled water produced at the plant and the water blended into the lake would be tested at different storage levels, and the quality of water would be tested for adherence to the drinking water standards.
Chennai city faces many water issues. To address these, multiple comprehensive water programmes and initiatives are needed. Significant efforts are needed in the sector, along with technological developments, to resolve the water woes affecting the city. With the city’s urban population set to increase in the coming years, it is very important to conserve and manage the available water resources.