资源环境科技发展态势分析平台

Across the world, the challenges of water supply are becoming more complex.  But imagine a water crisis in a city known for floods. 

In 2019, barely four years after unprecedented floods brought Chennai to a halt, a severe water shortage hit India’s southern metropolis, and officials declared "Day Zero". To save the city, the size of New York, water had to be brought in by train from some 200 kilometers away.

Much thought has since been given to Chennai’s water woes. Now, taking a leaf from Singapore’s acclaimed initiative, the city has begun to recycle wastewater at scale to meet the non-drinking water needs of its industries. 

Its two Tertiary Treatment Reverse Osmosis (TTRO) plants - launched in late 2019 - are the first facilities of this nature and scale in India. 

Once these plants ramp up to full capacity – of 45 million liters per day (MLD) each – they will be able to recycle about 20 percent of Chennai’s sewage, enabling the city to reduce its consumption of fresh water. 

The plants - at Kodungaiyur and Koyambedu – will serve industries in Chennai’s northern belt and the neighboring areas of Sriperumbudur, Oragadam and Vallamvadagal.

Industries here will receive water from sewage treatment plants that has been treated until it is of the same quality as the raw water that has traditionally been supplied to them. 

Recycled water adds a new, more sustainable water source for the city – one that saves both fresh and desalinated water, is always available and is more reliable than rainfall which can vary from year to year

Not surprisingly, this pioneering initiative has received several global and national awards, including the Global Water Award, and HUDCO’s 2019 award for best practices that improve the living environment and increase city resilience.

The Kodungaiyur plant was  supported by the World Bank, with co-financing  from  the central and state governments. Soon after construction began on this plant, the state government commenced work on the second plant at Koyambedu.

Chennai’s deteriorating water situation

Traditionally, this city of 9 million - which has some of the highest annual rainfall in India - has taken its water from four major lakes that are replenished by the annual monsoon rains. However, while Chennai needs around 1,200 MLD of water each year, these lakes, in their current condition, are only able to supply between 500 to 800 MLD a year, depending on the volume of rainfall that has occurred.

With demand for water far outstripping supply, the city has had to turn to other sources to meet its water needs, such as extracting precious groundwater or desalinating water at great expense.  

Recycled water therefore adds a new, more sustainable water source for the city – one that saves both fresh and desalinated water, is always available and is more reliable than rainfall which can vary from year to year.

In fact, a study by Anna University has calculated that by 2050, Chennai can meet up to 50 per cent of its water needs by recycling and reusing its sewage.

As urbanization proceeds apace, water resources dwindle, and rainfall becomes more unpredictable, each city will need to explore a variety of options to augment its water supply

As Ng Joo Hee, chief executive of Singapore’s acclaimed water utility has noted, “Water is an endlessly reusable resource and can be reclaimed and retreated time and again.” 

Augmenting water resources in a financially and environmentally sustainable manner

Water is becoming a major challenge for most Indian cities.  In 2018, a Niti Aayog report pointed out that India is suffering the worst water crisis in its history and that 600 million people – almost half the country’s population - face high to extreme water stress.

As urbanization proceeds apace, water resources dwindle, and rainfall becomes more unpredictable, each city will need to explore a variety of options to augment its water supply, depending on its geographic, geological, and socio-economic conditions. 

Managing citizens’ burgeoning demand, fixing the leaking bucket by attending to the all-too frequent leaks and losses, and conserving valuable ground water resources are all essential measures that each city will urgently need to act upon.  

Chennai too will need to address these issues and pick the low-hanging fruit by rehabilitating and expanding its reservoirs and lakes so that they can store more water.   

Only then can we assure future generations that the measures adopted today have been taken after careful thought, bearing both human well-being and the sustainability of the planet in mind.