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Cyber warfare is increasingly coming for U.S. water supplies.

Water providers in at least seven U.S. states have been targeted by cyberattacks over the past two weeks, according to multiple agencies including the FBI, the Environmental Protection Agency (EPA), and the Cybersecurity and Infrastructure Security Agency (CISA). Some officials indicated that as many as a dozen states could have been impacted.

Cyber warfare is increasingly coming for U.S. water supplies.

Water providers in at least seven U.S. states have been targeted by cyberattacks over the past two weeks, according to multiple agencies including the FBI, the Environmental Protection Agency (EPA), and the Cybersecurity and Infrastructure Security Agency (CISA). Some officials indicated that as many as a dozen states could have been impacted.

The hackers targeted components known as programmable logic controllers, which allow utility providers to manage the flow and even chemical composition of water supplies to the homes and businesses they serve, according to the agencies. In many cases, they “modified passwords to lock out operators and disconnected the [controllers],” CISA said in a recent advisory.

There are still no indications that the cyberattacks have caused major disruption or lasting damage to water supplies—at least some of the operators were reportedly able to switch to manual operations or use backup systems. However, CISA said that they were serious enough in some cases to have “resulted in boil water notices” to affected people.

The implications of the attacks are more severe, however. Programmable logic controllers help operators regulate the flow, distribution, and even chemical composition of the water supply. There have been a few close calls: In 2021, a hacker reportedly attempted to increase chemical levels at a Florida plant before being discovered in time, and in 2024, an attack caused a tank in Texas to overflow.

While the U.S. government has yet to officially attribute the latest attacks to a particular adversary or group, several reports as well as multiple former officials that Foreign Policy spoke to indicated that they are very likely linked to Iran. “I’m incredibly confident that these attacks are Iran,” said Cynthia Kaiser, who served as deputy assistant director of the FBI’s cyber division under former U.S. President Joe Biden. “The geopolitical motivation, capability, the recent history of targeting that sector … all of that points to Iran, and there’s not a plausible alternative.”

Hackers linked to U.S. adversaries like Iran, China, and Russia have a history of targeting U.S. critical infrastructure, with high-profile attacks such as the 2021 Colonial Pipeline hack (blamed on Russia) disrupting gas supplies to most of the U.S. East Coast. Other major hacks by operators affiliated with those countries have targeted telecommunications networks, medical providers, and food supplies.

This is also not the first time that U.S. water systems have been targeted, with both Iran and Russia linked to previous hacks of local water supplies in states such as........

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