Possible cyberattack on Cal Water raises concern in Central Valley

A possible cyberattack on California Water Service sent a fresh jolt through the Central Valley, where thousands of customers depend on the utility for daily water service. Cal Water said its preliminary findings showed no known operational disruptions to water or wastewater systems, including billing, and a spokesperson said a scan of internal IT and OT networks found no signs of compromise in its water production and delivery systems.

The concern reaches well beyond one company’s computer network. California Water Service says it serves about 497,700 customer connections in more than 100 communities across the state, and its parent company says those connections support about 2 million Californians. The company, formed in 1926 and headquartered in San Jose, serves communities from Chico to the Palos Verdes Peninsula, including Central Valley areas such as Bakersfield, Visalia, Chico and Selma.

The alarm grew after an image of a purported Cal Water bill circulated online, and reporting said an Iran-linked group called Handala claimed responsibility. That reporting also said the group claimed to have leaked about 5 gigabytes of data, including customer-billing information and administrative credentials. Cal Water has not confirmed an operational breach, and the company said it was working around the clock with cybersecurity, water security and quality assurance measures in place.

For Fresno County residents, the immediate question is whether tap water, wastewater service or billing could be affected. So far, Cal Water says the answer is no. Even so, the episode highlights how dependent local life is on systems that rarely draw attention until something appears wrong, especially in a region where water deliveries shape everything from household routines to agriculture and growth.

The warning signs also fit a broader national pattern. The Cybersecurity and Infrastructure Security Agency and the Environmental Protection Agency have said disruptions to drinking water or wastewater digital systems can carry significant community and critical-infrastructure impacts, and federal agencies, including the FBI and NSA, issued a joint advisory in April 2026 warning of an ongoing Iranian-affiliated cyber threat to U.S. organizations, including water-sector entities. The Government Accountability Office has also said EPA still needs a stronger strategy to address cybersecurity risks to water and wastewater systems.

Rep. Vince Fong called the incident a wake-up call and said he was in touch with the Department of Homeland Security. For Central Valley customers, the key fact remains that Cal Water has not reported service disruption, but the claim alone showed how quickly a suspected cyber incident can become a local infrastructure issue.