Salinity challenges and community adaptation: insights from coastal Bangladesh

Rising sea levels and increasing cyclone intensity are exacerbating salinity problems in coastal regions globally, threatening freshwater availability and public health. To address gaps in understanding community adaptation, we employed a multi-faceted approach comprising meta-analysis, water testing, surveys, focus group discussions (FGDs) and key informant interviews (KIIs) to: ( i ) examine rainwater harvesting trends, ( ii ) assess stored rainwater quality, and ( iii ) investigate community practices, perceptions, and health outcomes in coastal Bangladesh. Results of meta-analysis revealed that 14 out of 19 water quality parameters met WHO and national standards, while lead, fecal coliform, and total coliform exceeded acceptable limits. Heterogeneity analysis revealed considerable between-study variability for all parameters. Water sampling ( n = 45) confirmed elevated lead concentrations (0.03–0.33 mg L − 1 ), fecal coliform levels (18–68 N/100 mL), and total coliform levels (84–453 N/100 mL) across storage types. Household surveys ( n = 116) showed that 60% of households used rainwater for drinking and cooking during the monsoon, while 77% relied on stored rainwater in other seasons. Consumption of untreated water was associated with 2.4 times higher odds of diarrhea ( p < 0.05), and longer storage duration correlated with fewer health issues (ρ = -0.79, p < 0.01). Health issues were prevalent, with 41% of respondents reporting gastrointestinal problems and 37% reporting diarrhea. FGDs and KIIs identified water salinity as the primary concern and lead-based paint on rooftops as a potential contamination source. These findings underscore the need for integrated water management strategies, including regular tank cleaning, first-flush diverters, and community-based storage solutions to ensure safe drinking water in salinization-affected areas.