Late Wednesday evening the City of Corpus Christi notified Corpus Christi residents that an unknown chemical substance may have contaminated the City’s drinking water due to a recent back-flow incident in the industrial district.

As a precaution, the City is warning residents not to use the tap water for drinking, brushing teeth, showering, etc., until further notice.

At last notice, a petroleum-based substance was found in the water, according to the City. The Centers for Disease Control said the substance will not likely cause any side-effects, but the City is airing on the side of caution.

Boiling, freezing, filtering, adding chlorine or other disinfectants, or letting the water stand, will not make the water safe.

At last report, CCISD and Tuloso-Midway ISD will both have classes Thursday. Both districts say they have plenty of bottled water and hand sanitizer.