Chattogram faces water crisis as salinity and low river levels cut WASA production
Chattogram WASA reports that production from its four treatment plants—out of a total capacity of 50 crore liters—has declined by 8–10%, adding that production will continue to fluctuate until the start of the rainy season
Chattogram is grappling with a worsening water shortage as salinity in the Halda River and falling water levels in the Karnaphuli River sharply reduce freshwater production by the Chattogram Water Supply and Sewerage Authority (WASA), forcing rationing and leaving thousands of residents struggling for water.
Chattogram WASA reports that production from its four treatment plants—out of a total capacity of 50 crore liters—has declined by 8–10%, adding that production will continue to fluctuate until the start of the rainy season.
According to data from WASA, salinity in the Halda River—one of the city's two main water sources, along with the Karnaphuli—has increased since early February. As a result, the authority has had to reduce water production by around 2–3 crore litres per day at the Madunaghat and Mohra water treatment plants, each of which has a daily capacity of 9 crore litres. The rise in salinity often makes the river water unsuitable for treatment, forcing the plants to suspend operations for four to five hours at a time.
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In the Karnaphuli, lower water levels during tides caused the two treatment plants with a combined capacity of 28 crore litres to lose about 2 crore liters per day. In total, city dwellers were receiving 4–5 crore liters less water daily from the four plants, with residents in areas such as Patenga, Kathgar, EPZ, Halishahar, Pahartali and Chawk Bazar being supplied with water through rationing.
Chattogram WASA Chief Engineer Maksud Alam told The Business Standard that the authority normally collects water with a salinity level up to 250 mg per litre. This season, salinity at times rose to 2,900 mg, making it unsuitable for treatment, and forcing intake from the Halda to be halted for 4–5 hours a day. Also, with insufficient rainfall and lower water levels in the Karnaphuli, water intake there has sometimes stopped for an hour.
He warned that salinity is expected to rise again around full-moon tides next week and may continue through March. During summer, water demand is naturally high, which is why rationed supply has been necessary. To cope, 54 deep tube wells have been activated, supplying an extra 1–1.5 crore litres of water, he added.
WASA currently has about 97,000 water connections, with 97% residential and 7% commercial. About 10,000 customers reportedly do not receive regular water even after paying "line charges," and around 40% of the city's population has not yet been connected to WASA's supply.
Persisting salinity and effect of climate change
WASA data indicates that potable water demand in the port city increases by about 5 crore liters annually. Daily demand is projected to reach 63 crore liters by 2032 and 1.22 billion litres by 2042.
WASA collects raw water from three intake stations to supply its four treatment plants. Rangunia's intake can draw 30 crore liters per day, while Mohra and Madunaghat each have 9 crore liters capacity. A new intake at Boalkhali under the Vandaljuri project, with a capacity of 6.6 crore litres per day, was launched last year to serve areas outside the city.
Since 1994, Chattogram has struggled almost every year with salinity problems. When rivers receive insufficient upstream water in the dry season, saline tidal water from the Bay of Bengal moves upstream, a situation worsened by climate change and rising sea levels, allowing salt-mixed tidal water to enter the Halda.
Plans to address the crisis
To address the salinity problem, a new project costing around $40 million is being planned. A French consulting firm SUEZ submitted a concept paper in August 2022 recommending the construction of alternative intake stations, a pre-settlement reservoir and new treatment plants. The Economic Development Cooperation Fund has shown interest in financing the project, and feasibility studies are expected to begin soon.
The proposed infrastructure would include an intake and reservoir at Vandaljuri to collect 84 crore litres per day, a pumping station, a river-crossing pipeline beneath the Halda and Karnaphuli, and a new treatment plant capable of producing 20 crore litres per day.
Two additional plants are also recommended at the Mohra site. WASA engineers say the funding agency will send a team for feasibility assessment around May–June of this year.
