Salinization in coastal regions is a global challenge intensified by rising sea levels. Severe salinization in the coastal regions of Bangladesh forces communities to rely on stored rainwater, highlighting the need to assess its quality and storage challenges. This research adopted a mixed-method approach, incorporating water quality tests, household surveys, focus group discussions (FGDs), and in-depth interviews (IDIs) in the salinisation-affected region of Bangladesh. Twenty-three water samples from three types of water storage facilities were tested, 42 households were interviewed, and 4 FGDs and 4 IDIs were conducted to investigate rainwater quality, households’ challenges and adaptive practices, and stakeholders’ perceptions of drinking water management. The levels of lead (0.03–0.33 mgL−1), faecal coliform (12–71 N/100 ml), and total coliform (81–444 N/100 ml) in all sources exceeded the permissible limits of national and international standards. Household surveys exhibited diverse water storage methods, with 33% of households relying on commercial water tanks and 26% using a combination of earthen pots and plastic drums. However, 69% of households reported consuming untreated water, leading to widespread health issues, including diarrhea (79%), vomiting (67%), and skin irritation (57%). FGDs identified water quality and contamination as core challenges, with proposed solutions including rainwater harvesting, desalination facilities, and pond sand filters. The analysis of top keywords obtained from IDIs, such as ‘Water Salinity’ and ‘Rainwater Harvesting’, underscores the urgency of addressing water scarcity and contamination. These findings provide valuable insights into adaptive water management strategies, health risks, and sustainable solutions that can be applied to salinization-affected regions worldwide.