The Chattogram Water Supply and Sewerage Authority is in trouble as tidal saline water has entered the Halda river, water of which Chattogram Wasa uses to supply the city.

Due to the salinity, the water has become unusable, which is being supplied to different areas of the port city, as claimed by city dwellers.

Residents in Kattali, City Gate, Halishahar, and Patenga areas of the city have complained about the high salinity levels in the water supplied by Wasa for more than 15 days.

Rajib Raihan, of City Gate area, alleged that the water supplied by Wasa is not drinkable at all. "We are left with no other option but to collect tube well water from a nearby house."

Abdus Sabur, of Halishahar area, said they could not use the Wasa water for more than 15 days. "Despite lodging a complaint, the problem is yet to be solved."

Maksud Alam, chief engineer of Wasa, claimed the use of saline water will not have any harmful effects on human health.

He also said the water supplied to the city from Wasa is 100 percent sterile as per the WHO guidelines.

Asked, Idris Ali, former prof of Chittagong Government College's chemistry department, said, "350 to 400 mg per litre of salinity is definitely harmful to the human body, especially for children and older people."

Idris, who is also a water researcher of the Karnaphuli river, said the salt water can harm those with weak immune systems and cause digestive problems.

He also mentioned that the Wasa does not remove salt but minimises it from water.

According to Wasa sources, the city's daily water demand ranges from 46 to 48 crore litres. Presently, Wasa is supplying almost 46 crore litres of water from its four water treatment projects, with Unit-1 and Unit-2 of Rangunia Water Treatment providing 28.6 crore litres of water daily. The Madunaghat and Mohra Water Treatment Projects are supplying nine crore litres each.

However, because of a rise in salinity in the Halda river, the Wasa authorities had to reduce the collection of water from the Mohra Water Treatment Project. Currently, only 7.5 to 8 crore litres of water are being supplied from this source.

According to Maksud Alam, the salinity at the point where the Halda river meets the Mohra Water Treatment Project is 1,700 mg per litre, which is higher than the usual amount of 100 to 300 mg per litre.

The water supplied from the treatment after blading has a salinity level of 350 to 400 mg per litre.

Alam has expressed concerns that the water crisis may worsen if the dry season is prolonged.

The Power Development Authority's decision to reduce water release from Kaptai Lake has caused a problem, according to Engineer AKM Fazlullah, the managing director of Chattogram Wasa.

He explained that as a result of the reduced upstream water, tidal water from the Karnaphuli river is entering Halda, which, in turn, is affecting the purification process at the Mohra Water Treatment Project.

"Despite the purification process, some salinity remains in the water, and this has been a recurring problem for the past 15 days. The city dwellers have been informed about the issue through a media notice," he said.

To address the situation, Wasa is obtaining water from other treatment project and supplying it after the necessary treatment, he informed.

Additionally, the authorities are currently constructing another water treatment project to mitigate the crisis.

Rezaul Karim, chief engineer of the Power Development Board, South zone (Chattogram), said the water level in Kaptai Lake has decreased due to the dry season, which resulted in a decrease in electricity generation.

He emphasised that they have no control over this situation and have to rely entirely on nature.

"As a result of the receding water levels, only one unit at the hydropower plant is currently operational. If the dry season continues for an extended period, power generation could be further disrupted," he added.