New Delhi, March 22: Massive extraction of groundwater in the capital is depleting subterranean reserves and pushing this city of 14 million towards a dry future, according to experts.

While groundwater makes up half of the water used up daily in the capital, the table has dropped to 30 metres in some areas and even plummeted to below 100 metres in places, the experts said.

“We’re already living through a crisis, but no one knows when groundwater will be all depleted,” said Suresh Babu, assistant coordinator in the natural resource management unit at the Centre for Science and Environment (CSE) in New Delhi. In some areas, the extraction of groundwater could already be considered unviable because the water table has dropped far too low, Suresh said.

The rising demand for water without a commensurate increase in supply has led to over-exploitation of groundwater, a CSE report has said. At one site in South Delhi recently, engineers drilled to a depth of 130 metres, failed to find water, and gave up.

The Central Groundwater Board has also cautioned that groundwater levels in Delhi are “continuously declining” and that the quality is also deteriorating. In some parts of the capital, groundwater has high salt concentration.

Government figures show that Delhi uses 3,600 million litres of water each day. About 2,600 million litres come from the Delhi Jal Board ? the public supply system. In other words, 1,000 million litres per day are extracted from groundwater.

“But when you take into consideration losses from leaking pipes, the actual supply is about 1,800 million litres every day,” said Suresh. “The other 1,800 million litres ? or half of the consumption ? is from groundwater.”

“We’re living on tomorrow’s groundwater,” Suresh said.

A season of abundant rainfall can hoist up the water table. The groundwater level below the Jamia Hamdard University in the southern part of the capital rose from 45 metres to 38 metres after good monsoon rainfall four years ago.

“But since then, it has steadily dropped and is now about 63 metres below the ground,” said Ahmad Ali, executive engineer at Jamia Hamdard, who has been coordinating a water harvesting and groundwater recharging programme on campus.

Ali and his colleagues have drilled 13 narrow borewells, just six inches wide and 30 metres deep. After spells of heavy rain, water is collected in underground tanks for injection into these borewells to recharge the groundwater below.

“Things are going to be bad, especially in the southern part of the capital,” Ali said. In addition to rainwater harvesting and recharging through the borewells, he said, porous ground wherever it exists should be left intact to allow water to seep through.

Suresh said the conservation of water bodies ? lakes and ponds ? is another option that could help recharge groundwater. “We need a campaign to revive old water bodies. But the number and location of water bodies are still unknown,” he said.