Hydrogeochemical contrast between brown and grey sand aquifers in shallow depth of Bengal Basin: Consequences for sustainable drinking water supply

► Hydrogeochemical characteristics of brown and grey sand aquifers (BSA and GSA) have been investigated. ► The redox condition in BSA is confined to Mn oxy-hydroxide reduction. ► The redox condition in GSA is Fe oxy-hydroxide to SO42 − reducing. ► The trend of Mn enrichment in groundwater of BSA and GSA is opposite to the trend of As enrichment. ► Assessment of health risk for Mn is necessary before considering BSA as safe drinking water source.