Assessment of water quality and associated health risks in community-managed water systems in highland areas: A case study Chiang Rai province, Thailand.

Background: The present study addresses the persistent challenges associated with access to safe drinking water in highland communities of Thailand. Informal water supply systems, often managed by local villagers, rely heavily on untreated groundwater and surface water sources. This study assessed the quality of community-managed water supply systems and the associated health risks in Bandu and Nang Lae sub-districts, Chiang Rai Province, Thailand. Methods: To evaluate the quality of these community-managed water systems, a total of 66 water samples from 22 villages were collected and analyzed for physical, chemical, and biological parameters. Heavy metal concentrations were measured, and health risk assessments were conducted through dermal and oral exposure routes based on U.S. EPA guidelines. The One health concept was integrated to explain the association among human, animal, and ecological systems. Results: Monitoring data showed that many parameters exceeded the Provincial Waterworks Authority (PWA)'s standard, including pH (41 %), iron (32 %), lead (5 %), turbidity (2 %), mercury (2 %), and lack of free residual chlorine (100 %). The water samples showed signs of biological contamination. Total coliform bacteria were found in 39 % of the samples, fecal coliform bacteria in 27 %, and Escherichia coli in 9 %. Health risk assessments indicated that hazard quotients (HQs) and hazard indices (HIs) for heavy metals were less than 1, suggesting a negligible health risk. Total coliform bacteria levels in household water samples were positively correlated with diarrhea incidence (r = 0.54, p < 0.05). Conclusion: However, a positive correlation was observed between total coliform presence and reported diarrhea cases. The findings underscore the urgent need for improved water treatment practices, animal excreta management, ecological systems, and government interventions to ensure access to a safe water supply for highland communities in Thailand, which are under the one health concept. However, it highlights the need to focus on water quality, as in SDG 6 ensuring the availability and sustainable management of water and sanitation for all.