The people of the coastal parts of Bangladesh are insecure for safe drinking water. Therefore, the present research 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iron, manganese, cobalt, nickel, arsenic and chromium were determined through field work and, from published and unpublished literature. The results indicate that the arsenic concentration and electrical conductivity in shallow aquifers exceed WHO and Bangladesh standard limit. Additionally, chloride, total hardness, alkalinity, and lead exceed the WHO Bangladesh standards in both shallow and deep aquifers. In many cases, the turbidity of surface water both inside and outside the coastal embankments exceeds WHO and Bangladesh standards. The lead, chloride and manganese content and, DO and BOD in the Feni River also exceeds the WHO Bangladesh and BSTI limits. The analysis reveals that the deep aquifer is free from arsenic, while the shallow aquifer is significantly contaminated. Although the deep aquifers need precaution for salinity, alkalinity, total hardness, lead content etc. 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 intrusion of saline water 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.
Rashid et al. (Fri,) studied this question.