A hacker was able to remotely gain access to a Florida city's water treatment plant in an unsuccessful attempt to fill the water supply with a potentially harmful chemical, authorities said.
An unknown suspect was able to breach a computer system for the city of Oldsmar's water treatment plant on Friday and briefly increased the amount of sodium hydroxide from 100 parts per million to 11,100 parts per million, Pinellas County Sheriff Bob Gualtieri said during a news conference Monday.
Sodium hydroxide, also called lye, is used to treat water acidity but the compound is also found in cleaning supplies such as soaps and drain cleaners. It can cause irritation, burns and other complications in larger quantities.
A supervisor saw the chemical being tampered with and was able to intervene to reverse it. The sheriff said the city's water supply was not affected.
"At no time was there a significant adverse effect on the water being treated," Gualtieri said. "Importantly, the public was never in danger."
A plant worker first noticed the unusual activity at around 8 a.m. Friday when someone briefly accessed the system. At about 1:30 p.m., someone accessed it again, took control of the mouse, directed it to the software that controls water treatment and increased the amount of sodium hydroxide, The Tampa Bay Times reported.
Officials said other safeguards in place likely would have caught the change before it reached the water supply. The remote-access system the hacker was able to use has since been disabled.
Investigators said it wasn't immediately clear where the attack came from.
Oldsmar is about 17 miles northwest of Tampa. The treatment plant that was targeted provides water to businesses and about 15,000 residents, Gualtieri said.