Around 80 percent of daily water supply to city residents comes from groundwater, causing the water level to deplete by three metres a year on average, claims Dhaka Wasa.
The daily demand for water is around 240 crore litres in the capital. Around 20 percent of the demand is met with surface water from five treatment plants.
In a move to check groundwater depletion, three projects have been going on at a cost of more than Tk14,000 crore to treat river water and its supply to the capital.
But Dhaka Wasa still has not been able to overcome its dependence on groundwater as seen by its plan to install 95 more deep tube-wells and replace 285 others to extract 44.7 crore of water more every day.
In this connection, the Local Government Division has sent a project proposal titled "Emergency Water Supply" involving an estimated cost of Tk732 crore to the Planning Commission for approval.
Dhaka Wasa wants to complete the project work by 2023 with funds from the government exchequer.
The project is expected to be presented at the meeting of the Executive Committee of the National Economic Council (Ecnec) for approval on Tuesday.
The demand for water is increasing by 5 percent every year owing to the growth of population in the capital while the water extraction capacity of pumps is on the decline.
If this trend continues, the daily water demand in Dhaka will increase to about 350 crore litres by 2023.
Environmentalists opine if more groundwater were extracted, it would have a negative impact on the environment.
They think the proposed project is a disastrous one and neither is it farsighted, considering the demand for water in the future.
"The groundwater extraction should be brought down to zero as it is assumed that more than 70 percent of the country's population will live in towns by 2041. The main destination of these people will be Dhaka," said AKM Saiful Islam, a professor at the Institute of Water and Flood Management at Buet.
The groundwater level has been depleting fast owing to excessive extraction, he said, adding that the water level could not be refilled with rainwater during the rainy season as the number of nearby waterbodies is decreasing day by day, creating an adverse impact on nature.
Against this backdrop, he urged the authorities concerned to expedite the ongoing projects for the treatment of river water rather than approving a new project for extracting more groundwater.
Quoting recent research, ecologist Muhammad Azaz said 13 towns across four countries – Bangladesh, India, Nepal, and Pakistan – in the Hindu Kush Himalayan region are facing increased water insecurity in the wake of inadequate urban planning coupled with a rapidly changing climate.
The water level in many towns in Bangladesh has been declining drastically although there are enormous reserves of surface water, he said, adding that a project for extracting groundwater through deep tube-wells will never be sustainable.
A regeneration of 190 tube-wells and rehabilitation of 95 others will also be undertaken through the project. Besides, 250 pump houses will be built.
The Local Government Division said Dhaka Wasa started supplying water from the Padma (Jashaldia) Water Treatment plant recently in order to reduce pressure on groundwater. Work on two other plants is in progress. The massive demand for water can be met with surface water if all the projects can be completed by 2024.
Earlier, Dhaka Wasa implemented an interim water supply project at a cost of Tk612 crore to supply 90 crore litres daily as the ongoing river water supply projects did not get expected pace.