An Indian government think tank has warned that New Delhi is set to run out of groundwater within two years as climate change and dramatic population growth hit supplies.

Based on data collected from 24 of 29 Indian states, the National Institute for Transforming India (NITI) warned that the country's worst ever water shortage is likely to adversely impact some 600 million people.

It said that by 2020 some 20 Indian cities besides Delhi, including global information technology centres like Bangalore and nearby Hyderabad, were also likely to run out of groundwater, impacting over 120 million residents or nearly twice Britain’s population.

It cautioned that like Cape Town in South Africa, Bangalore too faced the grim prospect of ‘Day Zero’, when its water taps would run permanently dry if drastic measures to avert the looming crisis were not swiftly implemented.

“Critical ground water resources that account for 40 per cent of India’s water supply are being depleted at unsustainable rates” the NITI analysis declared and called for the immediate implementation of sustainable water resources.