CORPUS CHRISTI, Texas – UPDATE: EPA officials on Saturday said there have been four unconfirmed reports of possibly related symptoms from prohibited water use. Maps of TCEQ-EPA coordinated sampling locations can be found here.

ORIGINAL STORY: A chemical leak from an asphalt plant that led Corpus Christi officials to warn residents Wednesday not to drink the water was apparently reported internally a week earlier.

An internal email sent Wednesday by Susan Clewis, a regional director for the Texas Commission on Environmental Quality, indicates that a "backflow incident from a chemical tank" was reported Dec. 7 at Ergon Asphalt and Emulsions.

The email doesn't indicate who received that report, but the email indicates that the state agency only learned of the leak on Wednesday, when city officials warned the public.

The mayor of the Gulf Coast city of about 300,000 people has said local officials also only learned of the leak Wednesday.

Neither Clewis nor city officials responded to Friday requests for comment.

Ergon Asphalt and Emulsions released the following statement regarding the water crisis:

"Ergon Asphalt & Emulsions, Inc. has been in contact with the Texas Commission on Environmental Quality regarding the water supply in Corpus Christi and is working cooperatively to provide all information to ensure state officials can remedy the situation as quickly as possible.

"Ergon Asphalt & Emulsions, Inc. is working around the clock and is committed to providing support to assist in getting the drinking water supply back online."

Also Friday, some residents were being allowed to resume using tap water for limited use.

According to a city news release, residents who live in Zone 2 (see map below) were allowed to use tap water for bathing, showering, flushing toilets and washing clothes. City officials said that infants and young children should not bathe in tap water because they may swallow some water and there is still the potential for contaminated water. Individuals considered to be immunocompromised are also urged not to consume the water. All residents in the zone should not use tap water for drinking and cooking. Only bottled water should be used.

Residents who live in Zone 1 (see map below) were allowed to use tap water for drinking, cooking, bathing and all regular uses.

Residents who live in Zone 3 (see map below) are not allowed to use tap water for any reason, the news release said.

The city manager said plenty of bottled water has been donated to help residents.