Buying water will burn holes in farmers' pockets and in the ground water reserves.

After Chennai's water shortage, people are rushing to fix leaky taps and toilets in their homes. Good move, say water experts, but time to stop sweating the small sweat and tackle India's biggest water consumer. No, not factories, not power plants, not homes but farms.

Experts want an urgent rethink on growing water intensive crops like rice and cotton. Their export has made India the world's biggest virtual water exporter.

The crisis is dawning on farmers like Saddam Hussain and Alauddin Mondal of Deganga, 50 km north of West Bengal capital Kolkata. By mid-July, the paddy in their fields should have been knee high. But they are still waiting for monsoons to transplant saplings.

But there are no rains and they may have to buy ground water for their fields. They routinely use ground water for winter crops. But to pay for water in the monsoon, too, will spell twin disasters.

It will burn holes in their pockets and in the ground water reserves.

Indiscriminate farming of water intensive crops and export is untenable.

"I think I will stop cultivating rice. The cost of water we have to pump up from the ground is too much. Earlier, we got water at 20 feet below the ground. Now we use water from 80 feet below the ground," said Saddam Hossain.

"The water output has also fallen. We needed to pump water for 60 hours to farm paddy in one bigha of land. Now we have to pump water for 120 hours," he added.

Fellow farmer Alauddin Mondal said, "Pump owners have doubled their charges to pump up water, from Rs 10 to Rs 20 per hour. So from Rs 1600 to water one bigha of paddy, our cost has gone up to Rs 2500."

Hydrologists Dr Kalyan Rudra, author of a seminal book on Ganga-Brahmaputra-Meghna Delta, knows how much water there is.

Every year India gets 4000 billion cubic metres of rain. Of that, what can be used is 690 billion cubic metre surface water, 432 billion cubic ground water or in all 1122 billion cubic metres,

He also knows how the water is used: 6 per cent for homes, 6 per cent for industry, 3 per cent for energy and a staggering 85 per cent for agriculture.

Indiscriminate farming of water intensive crops and export, they say, is untenable.

In recent weeks, global bodies have confirmed India is a top exporter of virtual water

"4800 litres of water are needed to grow one kilo of Boro rice, Bengal's winter crop. If you export this one kilo rice, you are also exporting 4800 litres of water. This is called virtual water trade and right at this moment, India is the largest exporter of virtual water," said Dr Rudra who also chairperson, West Bengal pollution control board.

In recent weeks, global bodies have confirmed India is a top exporter of virtual water though it is a water stressed country. Those are exports the country can ill afford but what is the solution? Certainly not cutting back on production of key crops like rice. There is food security to consider.

"Food security is also required. At the same time water security is the most important requirement for the sustenance of our life," said Amaljyoti Kar of the Central Ground Water Board in Kolkata. "First we have to think of water security and think judiciously of food security."

For Saddam Hossain, Alauddin Mondal and Golam Farid, it is an impossible choice to make between: food or water. Their rice crops will fill many bellies, they know, but can potentially leave many people very thirsty indeed.

They are hoping they won't have to make the choice any time soon.