Chennai, the capital city of the southern Indian province of Tamil Nadu, experienced its worst water crisis in 30 years in 2019. It draws most of its water from four reservoirs that are usually filled by the annual monsoon. The 2018 monsoon brought just 60 per cent of the annual average rainfall, however, and, as of June, the reservoirs were at less than one per cent of their normal capacity.
Cometh the challenge, Cometh Chennai’s determination.
— Chennai Metro Water (@CHN_Metro_Water) November 5, 2019
Chennai Metrowater, the agency responsible for the city’s water supply, announced on 5 November that the city is officially no longer experiencing a water shortage and is water secure. Senior officials stated that the reservoirs that underpin Chennai’s water supply have about 114 gigalitres of water in storage, enough to last for about six months. The reservoirs hold about 360 gigalitres of water when they are full.
Even after a promising start to the north-east monsoon, the reservoirs that supply water to Chennai are still less than one-third full. Chennai Metrowater has increased the daily water supply to 650 million litres from 525 million litres. There is a daily water demand of 1,300 million litres, however, and Metrowater could only supply up to 830 million litres even before the shortage. It is estimated that 30-40 per cent of the water supply is lost to leaky pipes.
Water was brought from outside the city on trucks and trains to maintain supplies during the shortage. For the most part, that water was drawn from rural communities within a 55 kilometre radius of the city. The residents of at least one village protested against what they saw as the indiscriminate exploitation of their water resources by vandalising a water truck and blocking roads.
Water insecurity is common across India. According to the World Resources Institute, India is the thirteenth-most water stressed country in the world. It also has three times the population of the 17 most water stressed countries in the world, making its water security situation significantly more pressing.
Water was also drawn from aquifers beneath the city to maintain supplies. Groundwater supplies sharply declined across the city – by more than five metres in some locations. Even in neighbouring districts, outside of the city’s boundaries, the water table declined by almost two metres – three times the average rate across Tamil Nadu. That decline was possibly caused by trucks extracting water from those aquifers. According to a 2018 report published by a government affiliated policy institute, Chennai is one of 21 Indian cities that could completely exhaust its groundwater reserves by 2020. While that alarming claim is based on flawed research, and those cities will not completely exhaust their aquifers within the next 12 months, a reliance on finite groundwater reserves is not a long-term solution to water stress in India.
Rains in September and October recharged the city’s water reservoirs. Chennai relies on rainfall for most of its water supply and, as most of that rain falls in October and November, it requires large reservoirs to store that water for later use. On one day in September, enough rain fell to supply the city with water for 21 days. Not all of that water was captured, with most of it draining into the sea. While it is impossible to capture all of the rain that falls on the city, rainwater harvesting will help to ensure that more of the rain is captured and stored for later use.
According to Sekhar Raghavan, the Director of the Chennai Rain Centre, rainwater harvesting was made mandatory in Chennai in 2002-03. Even though only 50 per cent of the city’s buildings were in compliance with that directive, the harvesting of rainwater had a phenomenal effect on the city’s water security. Groundwater levels increased by six to eight metres across the city and the quality of that water also improved.
In June 2019, 11 of 24 groundwater monitoring wells had run dry. In the previous two years only two had gone dry by June. The rains increased groundwater levels across the city, but if surface water sources are depleted again it is only a matter of time before water levels decline. Water is still brought into the city via trucks, mainly to supply homes and other buildings that lack access to the piped water supply network. There are still 9,000 public water trucks that supply water to residents without any other access to water, another 5,000 private trucks cart water to wealthy residents who distrust the public water supply.
Chennai is water secure in only the narrowest of senses. While there is enough water in storage to last for about six months, there is every possibility that water shortages will return after that time. Water quality in the city remains very low, Metrowater continues to rely on an undiversified range of water sources, almost half of the water in the city’s water supply system is lost to leaks and a considerable amount of the population does not have access to that system at all. Chennai, like most of India, is still far from being water secure.