Cyberattacks on U.S. water systems that officials suspect may be linked to Iran-backed hackers have been reported in at least a dozen states, sources familiar with the matter told CBS News on Wednesday.

Those states include Michigan, Minnesota, Georgia, New Jersey and South Dakota. In Minnesota specifically, more than 30 community water systems were impacted, CBS News previously learned.

In Georgia, the Clayton County Water Authority, which serves 300,000 customers in the Atlanta area, said cyber activity last month caused a water pressure drop and forced the agency to issue a boil water advisory. Service was restored within hours, however.

Some utilities have lost critical remote-control capabilities, forcing operators to switch to manual mode. In several cases, the hackers gained remote access to pumps, valves and water pressure. 

So far, according to officials, the cyberattacks have had no impact on drinking water, which has remained safe.

On July 30, the FBI, Environmental Protection Agency and the Cybersecurity and Infrastructure Security Agency all warned that cyber threat actors had remotely accessed online infrastructure for water and wastewater systems in at least seven states, “resulting in a loss of monitoring and control functionality.” 

The water agencies were advised to disconnect their operating programs from the internet and strengthen their password protections and firewalls.

While federal investigators suspect Iran-backed hackers are behind the attacks, they have not made any formal attribution.

The tactics resemble a 2023 campaign by the CyberAv3ngers, a group linked to the Iranian Revolutionary Guard, which tapped into water-system controllers using default passwords.