Drinking Water Insecurity in the Coastal Parts of Mirsharai, Sonagazi and Companiganj Areas of Bangladesh: Water Quality Analysis

The people of the coastal parts of Bangladesh are insecure for safe drinking water. Present study is an attempt to delineate the water quality in the coastal parts of Mirsharai, Sonagazi and Companiganj areas. Various parameters of water quality such as free hydrogen (pH), electrical conductivity (EC), total dissolved solids (TDS), oxidation reduction potential (ORP), salinity, turbidity, dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), acidity, alkalinity, total hardness and nitrate, phosphate, sulphate, chloride, iron, manganese, cobalt, nickel, arsenic and chromium were determined through field work, available data and laboratory analysis. The results indicate that the arsenic concentration and electrical conductivity in shallow aquifers exceed WHO and Bangladesh standards limit. Additionally, chloride, total hardness, alkalinity, and lead exceed the WHO and Bangladesh standards in both shallow and deep aquifers. In many cases, the turbidity of surface water both inside and outside the coastal embankments also exceeds these limits. The lead, chloride and manganese contents, DO and BOD in the Feni River also exceed the BSTI limits. The analysis reveals that the deep aquifers are free from arsenic, while the shallow aquifers are significantly contaminated. Although, the deep aquifers need precaution for salinity, alkalinity, total hardness and lead contents. Correlation matrix analysis confirms that EC and TDS serve as reliable indicators of salinity levels in both shallow and deep aquifers. Principal Component Analysis (PCA) further supports this, showing that EC, TDS, and salinity are influenced by the saline water intrusion in these aquifers. Additionally, pollutants in both shallow and deep aquifers are positively associated with EC, TDS and salinity. Keywords: Drinking water insecurity, water quality analysis, coastal areas, Bangladesh.