Deliberate threats to Drinking Water Infrastructure in a Nordic context: Assessing multiple open information sources

Drinking water infrastructure, critical to a functioning society, is a potential target for intentional disruptive events, including sabotage, terrorism, and cyber-attacks. Understanding these threats is essential for hazard assessment, resilience planning, and public health preparedness, also in the Nordic countries. This study explores deliberate disruptions to drinking water systems and examines how open-source evidence can support hazard assessments and resilience strategies, addressing barriers such as access to sensitive operational information. We conducted a multi-source evidence assessment of openly available information, including a comprehensive peer-reviewed literature search, analysis of the Global Terrorism Database (GTD), and targeted review of grey literature and media reports focusing on the Nordic countries. References were screened for relevance to physical or cyber-attacks on drinking water infrastructure, with duplicates removed and titles and abstracts assessed independently by two reviewers. Peer-reviewed literature on deliberate attacks against drinking water is scarce, with only a few publications documenting historical incidents. GTD analysis identified 277 global incidents affecting water supply, mostly involving explosives, and revealed regional and temporal shifts in attack patterns. Grey literature and media reports provides additional insight, particularly for Nordic countries, highlighting that deliberate events are underreported and sensitive information is often restricted. Although documented events are limited, deliberate threats to drinking water supply remain a relevant security and public health concern. Strengthening structured information sharing and incorporating open-source intelligence into water utility hazard assessments can enhance resilience and support policymakers in safeguarding population health.