Identifying drinking water safety hazards throughout an Arctic community's water supply system

Arctic communities, ecosystems, and infrastructure are increasingly coming under scrutiny due to ongoing attempts at decolonization and reconciliation with Indigenous groups and the potential for geopolitical conflict in the region. There is also increased attention to the region from various industries because of its economic potential, especially as climate change allows for increased access for development. This increase in attention has highlighted the lack of understanding about drinking water sources and infrastructure in the Arctic. In this study we conducted extensive water quality monitoring in Cambridge Bay, an Arctic community in the territory of Nunavut in Canada, that uses a mixed utilidor and truck-to-cistern water system and has a history of water safety challenges. Three water sampling campaigns conducted in the spring, summer, and fall of 2024, targeted water safety hazards from source to tap that were identified by local stakeholders as well as water safety challenges described by researchers and engineering professionals in previous studies. These included microbial activity in cisterns, the formation of trihalomethanes (THMs) from natural organic matter (NOM), metal corrosion in buildings, as well as the impact of the spring freshet on turbidity and microbiological activity in the water supply and the treated water. The treated water from the trucks was found to have acceptable levels of free chlorine and low levels of microbial activity, measured as adenosine triphosphate (ATP), however, free chlorine residuals were low, and microbial activity were elevated in many cisterns. The concentration and composition of NOM in the source water varied from one sampling campaign to the next and both were found to have an influence on THM formation. Microbial activity increased in the source water and the treated water over the course of the spring freshet. Lead exceeded Canadian federal health-based recommendations (>5 µg/L) in tap water in 6/50 buildings based on random daytime sampling. Copper exceeded 2 mg/L in 9/50 buildings and 14/50 buildings had >1 mg/L. A water safety hazard risk analysis methodology specific to truck-to-cistern water systems in Arctic communities was used to score each hazard from low to very high risk. Of the eight hazards identified in this study, four were scored high or very high risk. Further investigation into seasonal impacts on source water quality and water treatment processes as well as corrosion in domestic plumbing systems in older buildings across the territory of Nunavut and in other Arctic jurisdictions is recommended to improve understanding of these water safety hazards and to identify appropriate interventions to address them.