Health Impacts of a Climate Change Adaptation Strategy to Address Drinking-water Salinity in Coastal Bangladesh

Background (brief): 1. Burden: Excessive salinity is common in groundwater aquifers across south-western coastal Bangladesh. Higher adult mean systolic and diastolic blood pressure and increased risk of gestational hypertension has been observed among those who drank tube-well water with high sodium content. 2. Knowledge gap: Managed Aquifer Recharge (MAR) systems, that inject freshwater into shallow aquifers, reduce drinking water salinity, have been successfully installed in the south-western area, providing year-round freshwater. However, the health benefits and risks of MAR water have not been measured. 3. Relevance: If drinking MAR water can reduce hypertension in adults and pregnant women, while showing minimal risk of microbiological and chemical contamination, scale up can be considered. Hypothesis (if any): Mean systolic and diastolic blood pressure will be lower among the adult population who drink MAR water compared to people drinking saline or brackish groundwater Objectives: To determine 1. If providing access to MAR water for drinking and food preparation reduces blood pressure among the adult population \> 20 years of age. 2. If providing access to MAR water for drinking and food preparation during pregnancy can reduce blood pressure among pregnant women. 3. If MAR water is contaminated with E coli and fecal coliforms. 4. Whether the MAR water is contaminated with dissolved constituents mobilized from aquifer sediments that are known to be harmful to human health. Methods: A stepped-wedge RCT will be conducted among communities before and after the intervention roll out. Study investigators will collect baseline information from all sites in the first monthly block (step) when no one will drink MAR water. There will be promoters who will convey messages regarding exclusive use of MAR water for drinking and cooking, at home and elsewhere. Measurements will be made by trained research assistants once every month. MAR water, pond water, gr