An intruder accessed a computer network in Oldsmar, Florida, on Friday and apparently attempted to pump sodium hydroxide, or lye, into the city water supply, the Tampa Bay Times reports.
A legitimate operator in the water-treatment system noticed the intruder changed settings to raise the sodium hydroxide concentration from 100 parts per million to 11,100, a potentially dangerous level. But the employee set the level back to the normal setting, so there was never any danger, officials say.
The Pinellas County Sheriff’s Office, along with federal agencies, are investigating the hack and have some potential leads, Sheriff Bob Gualtieri said Monday.
Even if the hack had initially gone undetected, other failsafe systems should have noticed the alkaline chemical being added and prevented it from poisoning water users, officials said.
Hacks targeting utility infrastructure have been relatively rare in the United States, with no known serious consequences, but they’re not unheard of. Attackers believed to be affiliated with Russia gained access to electrical control systems in 2017, though they didn’t do any damage. And some local utilities have been recipients of what appear to be targeted phishing attacks.