A computer hacker who remains unidentified increased the levels of sodium hydroxide in the water supply from 100 ppm to 11,100 ppm. The system was remotely accessed Friday February 5, 2021. This was caught by a plant operator who thought it was his supervisor accessing the system, upon finding this the levels were immediately reduced back to normal. It is not known whether the hack was done from within or outside of the US. Sodium Hydroxide is the chief ingredient in liquid drain cleaners, which is very corrosive and can cause irritation to the skin, and eyes, as well as temporary. If ingested it can cause damage to the mouth, throat and stomach, which can induce vomiting, nausea and diarrhea. Temporarily remote access to the water system has been disabled. This incident occurred in Oldsmar Florida, population 15,000.