Coastal Bangladesh faces severe water insecurity due to climate change and sea level rise (CCSLR), leading to anthropogenic and CCSLR-induced water salinization. A cross-sectional survey assessed perceptions and water security among 6092 ever-married women from 6698 households across 135 clusters in 6 high- and 3 low-salinity coastal sub-districts. 5420 household drinking water samples were tested. While 98% of households accessed drinking water that was technically “safe” (primarily deep tubewells: 46% overall, 70% low-salinity vs. 40% high-salinity), significant challenges persisted. Alternative sources were functional only in high-salinity areas. Intriguingly, improved water access was higher among the poorest (99%) than the wealthiest (93%). Virtually all households (100%) observed climate change impacts (temperature, rainfall, disaster intensity/frequency, salinity intrusion), with 93% experiencing at least one disaster in the past decade. Salinity intrusion was a major reported concern, particularly affecting water availability and quality for household use in high-salinity areas. Gendered water insecurity due to salinity was prevalent in high-salinity areas: long-distance travel for water (31%), saline water use during menstruation (25%), drinking saline water (18%), reduced consumption (11%), physical discomforts (17%), and water purchase (18%). Surface and shallow tubewell water, primarily used for bathing, cleaning, and menstrual hygiene, was perceived as unsafe by 46% and 90% of women, respectively. Water collection, primarily by women (69%), involved long distances (> 1 km: 23%) and time (>1 h: 17%). Water testing indicated 81% met the national salinity standard (≤ 1000 mg/l), but post-monsoon sampling limits the conclusiveness. Climate-adaptive water solutions embedding health considerations are urgently needed for coastal Bangladesh.