Chennai Petroleum Corporation, then Madras Refineries, had to shut operations in the late 1980s due to water scarcity.

Today it buys sewage and treats it to meet its raw water requirements. Coca-Cola has been asked to stop using ground water by the authorities in Kerala, and cotton knitwear exporters in Tiruppur in Tamil Nadu have approached the government to privatise water supply in order to ensure regular availability.

In other areas, such as Uttaranchal, attempts are being made to hand over drinking water schemes to local communities, to see if this improves availability.

Shortage of water has meant that, in states like Kerala, water charges can be as high as Rs 550 per kilolitre -- households in Delhi pay 35 paise per kilolitre -- for large users.

According to the International Water Management Institute, much of western and peninsular India will face an acute water scarcity in the next 25 years: the institute projects that a fourth of India's harvest will be at risk due to groundwater depletion.

According to The Energy and Resources Institute, while it costs around 85 paise to pump out a cubic metre of water at a depth of 15 metres, the cost goes up to Rs 2.10 at 35 metres.

The water table in Kurukshetra in Haryana has been falling by around half a metre a year. In four years, according to TERI, the cost of pumping water in the area will go up by Rs 7 crore (Rs 70 million).

Apart from Punjab and Haryana, where the problem is serious, Tamil Nadu and Rajasthan are other states where the water table is falling fast because of over-exploitation.

The overall demand-supply situation appears comfortable -- India has 1,086 billion cubic metres of water available against the demand of around 600 billion cubic metres now -- but the situation is deteriorating rapidly.

Usable water in the country, per capita, has declined from 3,500 cubic metres in 1947 to 1,200 today; by 2017 the level will fall to below 1,000 cubic metres. India is now in the water "stress" zone, by 2017 it will be in the "scarcity" zone, by 2047 it will be in the "absolute scarcity" zone.

At the micro level, the situation is already desperate, with people in a third of India's cities getting under 100 litres of water a day against the basic norm of 135 litres.

When it comes to quality, matters are worse since under a fourth of domestic waste water is treated. Over the last decade, pollution levels in surface water have gone up by a fifth.