The Millennium City is set for a catastrophic water and sewage system collapse by 2021. If the latest report of Centre for Science and Environment (CSE) is to be believed, the city would "drown in its own excreta". The report — "Excreta Matters" — released on Thursday has thrown up some startling revelations that point towards severe water demand-supply mismatch, depleting ground water levels, obscene amount of sewage generation and acute sewage management crises by 2021.

According to the report, with a projected population of 3.7 million by 2021, Gurgaon will have a water demand of 666 million litres per day (MLD) but it will be able to generate only 573 MLD.

The city will generate 533 million litres of sewage, but its capacity to treat waste water will fall short at 255 MLD.

The report also says the amount of groundwater extracted in Gurgaon is more than thrice the amount of water replenished by rain. It says over 250 construction projects across the city have been extracting groundwater.

It also claims that only 50-60% of the total sewage generated by the city is collected. It flows into the Najafgarh drain and through it, into Yamuna river. There is no account of the remaining 40-50% sewage.

"This is a deadly spiral. The challenge is, how can cities grow in a manner in which they use minimal water and generate minimal waste," CSE director general Sunita Narain said.