According to the estimation of the United Nations, by 2050, two-thirds of the world’s population will be forced to live with economic, social, and environmental challenges due to water scarcity. North Africa, the Middle East, and Asia will be the most affected regions. Global warming will further exacerbate the water crisis, along with increasing salinity levels in freshwater sources.

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Since 2007, the issue of salinity in the water supplied by Chottogram WASA at a specific time of the year has become a severe problem in Chattogram, the country’s second-largest metropolis and commercial capital. While the presence of excessive salinity in the water was first detected around March-April in 2007. In December 2013, the salinity levels had exceeded the tolerance limit. In recent times, the WASA authority has regularly asked people to take precautions in drinking water by releasing advertisements in newspapers. Within just twenty years, both the severity and duration of salinity have increased significantly. The problem of salinity has become severe in all the areas of the city where water is supplied from the Halda River. It is important to note that approximately 40% of WASA’s water supply in the city comes from the Halda River. The problem becomes more severe when the salinity level in Halda’s water increases.

The flow from the Karnaphuli River, rainwater, the natural flow of groundwater, and water from the Kaptai Lake are primary sources of water for the Halda River. Karnaphuli River’s water enters the Halda during high tide and maintains a continuous flow throughout the year. In monsoon, the Halda receives surface runoff from rainfall. The natural groundwater flow depends on the infiltration of sufficient rainwater. If there is insufficient infiltration, this process becomes obstructed except during the monsoon season. When the water level of the Kaptai Lake remains within a normal range, the Halda receives fresh water from it. Apart from the Karnaphuli River, the other sources provide fresh water to the Halda. If any of these sources face obstructions in water flow, it leads to severe disruptions in Halda’s water supply. Since 2007, during periods of increased salinity in the Halda has been observed that when the water level in Kaptai Lake falls below normal, the dam authorities stop supplying water to the Halda. As a result, the Halda is deprived of freshwater.

On the other hand, one of the primary sources of freshwater for the river is the percolation of groundwater. The section of the Halda that flows past Chattogram City has an almost non-existent percolation process. This is because percolation requires an adequate level of groundwater. It is worth noting that approximately 60% of the water supplied by WASA in the city comes from groundwater sources. Due to WASA’s inability to meet the city’s water demand, most homeowners extract groundwater through tube wells for their personal and tenants’ use.

The unregulated extraction of groundwater is disrupting the natural flow of freshwater into the Halda and increasing salinity levels. As a result, people in Chattogram rely more on groundwater due to the high salinity in Halda’s water. This is gradually making groundwater saline. In areas like Colonel Hat, Halishahar, Agrabad, Bakalia, Dewanhat, Badurtala, Mohora, and Panchlaish, groundwater now has been salty taste. Each aquifer has a limited water supply, and excessive extraction disturbs the balance by causing salinity. In some places, saline water exists beneath the groundwater table, and over-extraction brings it up. Additionally, arsenic is now found in tube well water as well.

Rising sea levels from climate change are also pushing salty water from the Bay of Bengal into the Halda. Furthermore, even the minimal groundwater that remains is becoming saline before entering the Halda. Consequently, WASA is supplying this saline water to city residents. Desalination of water for public supply is extremely expensive in a country like Bangladesh. Therefore, WASA has no alternative but to continue supplying this water. Therefore, the problem is only expected to worsen over time. However, with proper initiatives to possible to mitigate the issue to some extent.

To solve this problem, the first step that needs to be done is that stop extracting groundwater by all legal and illegal means, including by WASA itself. To achieve this, WASA must establish a strong monitoring system. If the extraction of groundwater is not stopped immediately then the city dwellers will have to face a terrible disaster soon. In addition to stopping the extraction of groundwater, illegal water theft and unauthorized water businesses operating under the guise of WASA’s services must be stopped. WASA must ensure an adequate and reliable water supply throughout the city. If these measures are effectively implemented, it will soon be possible to put an end to uncontrolled groundwater extraction.

Chattogram City has numerous small and large water reservoirs, including Foy’s Lake, Askar Dighi, and Boro Dighi. These reservoirs must be restored and used to store water during the monsoon season. Additionally, there are many low-lying areas around the city. Water conservation should be done there during the rainy season as well. From all these reservoirs, it seems possible to supply the residents with water purification for at least six months a year. This approach has already proven effective under the supervision of the military during a previous interim government’s tenure. However, a detailed study must be conducted to determine the exact duration and how many families can be served properly.

The conservation of these reservoirs, implementation of water supply systems, and all associated activities should be funded by collecting revenue from the households that will receive water from these reservoirs. In particular, those who currently extract and use groundwater should contribute to this funding. Since they already invested a significant amount in extracting groundwater, they should now redirect that investment toward the city’s water supply system for the sake of environmental protection and to prevent a severe crisis in Chattogram. Moreover, they must be compelled to do so to ensure the sustainability of the water supply.

On the other hand, initiatives should be taken to encourage residents to practice rainwater harvesting during the monsoon season. Alongside awareness programs, the necessary technology for rainwater harvesting must be provided. For this, government experts, as well as private organizations, universities, and research institutions, should be engaged as needed. That way, this approach could eliminate the need for WASA to supply water for at least three months during the prolonged monsoon season. This would not only reduce government expenditure but also help alleviate the city’s water crisis and lower the risk of environmental degradation in Chattogram.

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On the other hand, it is essential to protect all open spaces, gardens, hills, and undeveloped areas in the city to ensure proper water infiltration.

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Unplanned sluice gates must be opened. This will create opportunities for fresh water to flow into the Halda River, which will help reduce its salinity.

Immediate and effective measures must be taken to address these issues. Otherwise, the residents of Chattogram will soon face a severe crisis, at which point no action will be sufficient to prevent the catastrophe.