Major metros like Delhi and Mumbai face huge water and environmental crises as infrastructure tries to keep pace with the increasing population, says a new study of 71 Indian cities.
The report, Excreta Matter, prepared by the Centre for Science and Environment (CSE), comes at a time when India is urbanising at the highest rate in the world and half of all Indians are expected to be living in cities by 2050.
"If we do not get the arithmetic of water waste right, it will drown us in its own excreta," said Sunita Narain, CSE's director general.
The study presents the dirty picture of Indian cities' capacity to treat less than half the sewage they generate. Moreover, the dirty sewage generated flows into rivers like Yamuna in Delhi, Mithi in Mumbai and wetlands in east Kolkata. Even a modern city like Bangalore is able to treat just 30% of its sewage.
What is worse, the treated sewage is not even utilised for non-food or non-bathing purposes. "Most cities don't have water management plans," the report says.
The study also points out another major flaw - water loss during distribution. Over 35% of water in Delhi and about 30% in Mumbai is lost because of leakages, the report says.
Delhi extracts around 12% of its supply of 1,824 million litres per day (MLD) from the ground but fails to replenish the same amount by way of water harvesting. The availability of water in certain regions is around 63 metres below the ground.
Even though the capital's population has increased by 50% since 1994, the increase in water connections is just 3%, the report says, indicating that the Delhi Jal Board has failed to augment water supply in the city.
Mumbai fares no better. Residents of high-rises receive about 220 litres per capita per day whereas those in slums get less than 40 litres. With its population estimated to be 15 million in 2011, it needs about 1,300 MLD to meet the demand.
Kolkata is slightly better than the two in meeting its water requirement but may fall in the same trap if its sewage treatment capacity is not increased. From a water-surplus city, Kolkata is turning into a water-deficient city.