The old channel of the Buriganga is now like a mere canal in the Vakurta area, connecting the Dhaleshwari and the Turag and dividing the Savar and Keraniganj upazila.

Whether it is the causal effect of the WASA's installation of a good number of deep tube wells in the area or not, the residents of Vakurta are struggling to get water supply via their hand tube well due to the fast-declining groundwater level.

"All of us are facing the problem -- none can use their hand tube wells anymore," said Lokman Hossain, a grocery shop owner on the banks of Buriganga.

The hand tube well in Lokman's home, installed by his grandfather, is 200 feet deep. But these days, it cannot lift any groundwater for the family's consumption.

Lokman blames the WASA for their water crisis as the numerous deep tube wells installed by the authorities have desiccated the area.

To get any water from the ground, the residents have to install a powerful pump, which costs Tk 40,000 and is beyond the affordability of many in the area.

"We feel helpless," he said, adding that they are getting their water supply through a pipe from their neighbour's home, who could afford to install a pump.

Lokman's neighbour Mamtaz Begum is more resentful.

"WASA is taking water from our village for the city dwellers," she said.

It is the same scenario in Bauta village in Keraniganj.

The residents get water through their tube well only in the rainy season and nothing during the dry season spanning the months of March to June, said Akhil Chandra Das, a local.

The problem persists in all villages in the area including Vakurta, Baherchar, Battoli Bazar, Balughata and Bauta after WASA installed pumps about a decade ago.

Even though this tubewell is 200 feet deep, the declining groundwater levels prevent it from lifting water during the dry season. Photo: Palash Khan

Several lakh residents of Bhakurta and Tetuljhora unions in Savar and Taranagar union in Keraniganj are in the same boat.

As many as 20,000 hand-driven tube wells in the area have gone dry.

Dhaka WASA, however, denies drying up the grounds.

A total of 42 deep tube wells have been installed in the Vakurta area and 1,227 in Dhaka and its surrounding areas, said Abdul Kader, deputy chief of public relations at Dhaka WASA.

All those pumps are extracting water from the aquifer 400 to 1,200 feet deep, he said, adding that about 2,000 private deep tube wells are also in operation in the city.

The existing water services heavily rely on groundwater, with about 70 percent of the water supply provided by Dhaka WASA being sourced from aquifers, he said.

The rest comes from refining the waters of Shitalakhiya, Buriganga and the Padma by the five water treatment plants dotted around Dhaka and its surrounding areas.

Dhaka WASA produced about 2,680 million litres of water (mld) per day for 20 million residents of the capital and its suburban areas, according to its annual report of fiscal 2022-23.

As per Dhaka WASA's projection, the demand for water this year would be 3,598 mld per day, meaning more water has to be extracted from the aquifer -- an unsustainable practice, as per the water supply master plan of Dhaka WASA published in 2014.

Despite annual recharge every year, there is an overall declining trend in groundwater level due to over-extraction, according to the master plan.

Subsequently, it advocated shifting the bulk source of water from groundwater to surface water to limit the supply from deep tube wells to 1,260 mld per day.

A large-scale extraction from such aquifers may cause a permanent depletion of water level, said Anwar Zahid, a senior groundwater researcher.

In the 1970s, the groundwater level was less than one metre below the surface. Now, it has dropped to 70 metres, according to his research.

In 2022, the groundwater levels in the city's densely populated areas of Mirpur, Monipur, Sabujbagh, Tejgaon, and Basabo were 66, 63, 66 and 63 metres below the surface respectively.

In contrast, in river-adjacent areas of Mohammadpur, Gandaria and Hazaribagh, the levels are at 36.5, 21 and 33 metres respectively.

Every year, the groundwater level is depleting by one to 1.5 metres.

If the government does not take any measures, the groundwater level in densely populated areas will drop to 100 metres by 2050.

The key principle of sustainable groundwater management is ensuring that annual water extraction does not exceed the natural recharge rate.

"However, in Dhaka, this balance has been dangerously disrupted," Zahid said.

The aquifers in the Dhaka metropolitan area are permanently losing more than 500 million cubic metres of water annually, he said citing a study. And this is not being replenished through natural recharge.

It is imperative to create opportunities for artificial groundwater recharge using various methods to improve the water table, he said, adding that the quality of water used for recharge must be ensured.