The summer’s cyberattacks by Iranian hackers on water systems in 12 states underscored how vulnerable U.S. water systems are to foreign adversaries. A broad attack on water infrastructure could have consequences comparable to a public health crisis that impacts the country’s entire population.
The threat to water has long been clear. As the 2026 Annual Threat Assessment from the U.S. intelligence community states “Cyber actors from China, Russia, Iran, North Korea, and ransomware groups . . . pose critical threats to U.S. networks and critical infrastructure.”
Advances in artificial intelligence have heightened those vulnerabilities. Advanced AI models, such as Anthropic’s Claude Mythos, have demonstrated the ability to identify thousands of zero-day vulnerabilities in critical software systems, including major operating systems and browsers. Other systems, including some developed in China, are demonstrating similar capabilities. AI systems can now “plan, test, and execute attacks in rapid cycles,” ranging from minutes down to seconds.
U.S. water systems are vulnerable to cyberattacks for technical, legal and practical reasons.
Technical: About 80% of U.S. water systems lack even basic cyber hygiene, a weakness exploited in the summer attacks. Even systems that serve most of the population (approximately 450 large and 4500 medium-sized water systems) have not adopted advanced cybersecurity capabilities used in other sectors where failure can have catastrophic consequences, including aviation, rail, mass transit, medical devices, finance, and nuclear power.
Legal: The Environmental Protection Agency lacks clear statutory authority to impose broad cybersecurity requirements on water systems. In 2023, EPA issued a memo interpreting existing regulations to strengthen the cybersecurity of water systems. The action met widespread opposition from the water sector as well as formal legal challenges, and the EPA ultimately withdrew the memo. The agency retains limited authority. It can require water systems to complete risk and resilience assessments, maintain emergency response plans and, in emergencies, address critical cybersecurity flaws.
Practical: Most U.S. water systems are small. Some 45,000 serve 3,300 persons or fewer. Because of their size, many fall outside the EPA’s regulatory authority and below the “cyber poverty line,” lacking the funding, staff and expertise necessary for effective cybersecurity.
Not surprisingly, the summer attacks drew attention from the administration and Congress. The EPA ,in partnership with the FBI, and CISA each issued guidance on remedial actions, including disconnecting operational technology, from the internet where feasible and adopting robust password practices.