For thousands of people in coastal Bangladesh, collecting rainwater has become the only source of obtaining drinking water as the changing climate has increased the salinity in local groundwater.
Asaduzzaman, 36, is a father of two children from the Shyamnagar upazila or sub-district in the southwestern Satkhira district. His elderly parents and his elder brother's family live with him.
The family of six adults and four children relies on rainwater harvesting due to the high presence of salinity in natural sources and lack of other means of purifying saline water.
"Our village, which has a population of roughly 6,000 people, has only two deep tube wells. However, it is no longer drinkable due to high saline levels. High salinity is also seen in the water of natural ponds and rivers. Therefore, we rely on rainwater harvesting," he told Anadolu Agency.
The government has installed a 3,000-liter tank for rainwater harvesting on the rooftop of their house, which can meet water requirements for about 10 months, he said, adding: “We have to manage alternate sources for two months during the dry season.”
“We have been living in the village for decades, but have never faced the crisis we are experiencing now. Frequent cyclones and changing weather have taken the salinity to such a level that we cannot use nearby water from natural sources anymore,” he said.
Agricultural cultivation has also largely declined due to salinity, he added.
Monoara Khatun, 41, who is also a project beneficiary, echoed this view.
She said the government bears the majority of the expense of installing rainwater harvesting equipment and that rainwater is currently used by the majority of the homes in her village.
Md. Shahidul Islam, a District Public Health Engineering Department officer, told Anadolu Agency that almost 58% of fresh drinking water demand is met under government arrangement in the Shyamnagar sub-district.
“We have already provided rainwater harvesting tanks to 1,680 families, while 312 homes are in line to receive one soon. Tube wells are not suitable in the area due to the salinity in natural sources and faltering saltwater is a costly method,” he added.
They discovered a significant degree of salt in the region, with 4,400 milligrams per liter (mg/L) compared to the permitted threshold of 1,000 mg/L in the coastal area. A single reverse osmosis water purification system costs 3 million Bangladeshi Taka (approximately $35,000). Therefore, he maintained, rainwater harvesting is still a cost-effective and healthy practice.
He also said that frequent cyclones and weak embankments have caused saline water to enter the area, depleting freshwater sources, which he described as a major concern for the region.
Some NGOs are working with the government to install more of these rainwater collection systems in Satkhira district due to rising salinity due to climate change, he added.
Additional investments are needed in the countryside, however, to install more rainwater harvesting and develop buildings with the capacity to put tanks, he proposed, and private organizations may help.
Rainwater harvesting can help other areas
Expanded salinity has resulted in a severe shortage of potable water in coastal regions, while reliance on groundwater has increased more than ever in other areas.
The quantity of arsenic in the groundwater is more than tolerable in many areas, including northern Bangladesh. And the groundwater level in the capital alone is dropping at a rate of around five feet each year due to excessive groundwater consumption, according to 2030 Water Resources Group, a public-private initiative hosted by World Bank.
Rainwater can be an alternate supply of fresh and safe water in such a case, according to experts, because the practice of storing rainwater during the rainy season and utilizing it at other times of the year is a quite old practice.
However, the use of rainwater as a source of drinking water has decreased. According to the Bangladesh Bureau of Statistics (BBS) report published in June this year, rainwater usage as a source of drinking water remained 0.2% in cities and 0.3% in rural areas.
South Asia Regional Director for WaterAid Md Khairul Islam told Anadolu Agency: "We can assess the result of rainwater harvesting in the coastal area and extend the method across the country in order to cut the pressure on groundwater."
According to their water policy, “we are supposed to use 50:50 ratios of ground and surface water sources. But we are relying more on groundwater due to contamination on surface water,” he added.
“We have some good examples of ready-made garments and factories that use rainwater for their processes. We can acknowledge and promote such initiatives,” he suggested.
Earlier, Dhaka city authorities had announced that city buildings with rainwater harvesting equipment would be exempt from paying holding taxes.
“Now, our national building code keeps provision for rainwater harvesting for buildings in cities, including the capital Dhaka, and we should concentrate on implementing the building code nationwide,” he stressed.
“Building construction companies should also be familiar with the method as it does not cost much to install a plant,” he added.