Physicochemical and Microbiological Quality of Potable Water Supplied by DWASA in Dhaka City of Bangladesh

Abstract

Dhaka is the largest and fastest-growing urban city in Bangladesh with a population density of 44,500/km 2. Dhaka Water Supply and Sewerage Authority (DWASA) is the sole legal entity to develop and maintain a water supply system for city people. 78% DWASA water comes from underground-which leads to incremental depletion of groundwater. In this condition, reducing groundwater dependence and switching to surface water is the only way forward. Growing and increasingly wealthier population, climate change and the urbanization process deteriorate the Shitalakshya River which is the surface water source of DWASA. The purpose of this study was to investigate the DWASA supplied water quality around Dhaka city. Physicochemical and microbiological Parameters were analyzed by American Public Health Association (APHA) standard methods. The measured pH value (6.58-7.03) and Dissolved Oxygen (DO) value (6.10-7.50 mg/L) of samples indicate safe potable water. Calcium and Magnesium were found at a significant level. Both of these elements are essential for the human body. There were no heavy metals contamination in water supplied by DWASA. Total Coliforms and Fecal Coliforms of all samples showed less than 0.2 MPN/mL (most probable number <0.2 indicates absence of test organism in 1 mL). Total Viable Count (TVC) of all samples were less than 100 cfu/mL. The observed result was compared to acceptable limit of drinking water of Bangladesh Standards and Testing Institution (BSTI) and Environment Conservation Rules, 1997, Bangladesh guideline. This study demonstrated that in general the potable water quality status of Dhaka city ranged from excellent to good.