Vulnerability of drinking water supply and respondent's perception on the quality of water supply in Dhaka City, Bangladesh

Dhaka, the capital of Bangladesh, has been consistently ranked as one of the most populated and polluted cities in the world. The city has been experiencing severe groundwater declination and widespread surface water pollution, which are its main drinking water sources. The sustainability of water resources is one of the largest issues facing by this megacity. The research aimed to evaluate the groundwater and surface water quality in Dhaka with respect to the drinking water standard of the Environment Conservation Rules (ECR)-1997, assess the vulnerability of drinking water supply, and explore the respondents' perception regarding the quality of supplied water. The study revealed that Iron (Fe) and Manganese (Mn) concentrations in groundwater were found to be in alarming condition in different areas of Dhaka during the years 2015-2019. Groundwater is drastically depleting over the years which requires ensuring sustainability. By using the Canadian Council of Ministers of the Environment (CCME) method, the Shitalakhya, Dhaleshwari, and Turag Rivers have a Drinking Water Quality Index (DWQI) value of less than '44', signifying that the water quality is poor and unsuitable for drinking and domestic purposes. The research also found a strong positive relationship between increasing population and groundwater depletion, a moderate positive relationship between rising temperature and groundwater depletion, and an inverse relationship between decreasing precipitation and groundwater depletion over the last 25 years (1990-2014). Regarding the vulnerability of drinking water supply, population density, groundwater depletion trend, and surface water quality were categorized as 'high' vulnerability factors. About 36% of the respondents living in Dhaka South City Corporation and Dhaka North City Corporation areas claimed that supplied water quality is poor. Nearly all surveyed households (98%) used water purifying techniques before drinking supplied water. More interestingly, over two-thirds (77%) of the total respondents showed interest in paying more for improved drinking water service over the current water bill. Some economic models were suggested as policies for sustainable water resource management in the greater Dhaka city.