CORPUS CHRISTI, Texas -- There were three reports of dirty water before the 300,000 residents of Corpus Christi were told not to drink the city’s water due to a chemical leak at an asphalt plant, a top Corpus Christi official said Saturday, adding that the city has not found evidence of water contamination.

Water use was resuming for some parts of the city - some fully, others for washing purposes only, city spokeswoman DeAnna McQueen said Saturday.

CBS Corpus Christi affiliate KZTV reported recommended levels of water use in different districts were broken down by three zones.

In zone one, water could once again be used for all activities. Zone two was cleared for partial use and people were allowed to do limited activities such as bathing and showering.

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“However, due to the potential for contaminated water, infants and young children should not bathe using water since they may swallow some of it and additional water testing is needed,” the city said in a statement posted online on Friday.

Others including individuals undergoing chemotherapy and those with HIV/AIDS should also avoid consuming the water, and the zone should not use the water for drinking or food preparation, the city said.

The third zone still had a total ban by early Saturday afternoon.

Assistant City Manager Mark Van Vleck said the first “dirty-water report” came Dec. 1 from the Valero-owned administration building at the asphalt plant that’s leased to Ergon Asphalt and Emulsions. City workers flushed the pipe. A second report came from the same building Dec. 7, he said, and the main was flushed again.

“We get dirty water reports all the time,” Van Vleck said of the first two, saying old cast-iron pipes are usually the reason.

But Monday, Valero workers told the public works department “something white and sudsy” was in water at the administration building. City workers determined there was a leak in a chemical tank at the asphalt plant and on Tuesday determined there was a backflow problem.

The city told the Texas Commission on Environmental Quality about it Wednesday, Van Vleck said, and hours later,the state banned use of public drinking water. Mayor Dan McQueen has said local officials only learned of the leak Wednesday. TCEQ officials did not respond to a request for comment Saturday.

Van Vleck cautioned that the investigation is ongoing, “so we don’t know what happened.” He added: “We do not know (if there was contamination) because we can’t prove it.”

A TCEQ report obtained Friday indicates that a combination of Indulin AA-86 and hydrochloric acid leaked into the water supply. Indulin is an asphalt-emulsifying agent that’s corrosive and can burn the eyes, skin and respiratory tract if a person comes into contact with concentrated amounts. The amber liquid is considered a hazardous material by the Occupational Safety and Health Administration.

“You don’t expect to see it in water,” Texas Commission on Environmental Quality spokesman Terry Clawson said Friday.

Ergon has said it has been in contact with the TCEQ and was “working cooperatively to provide all information to ensure state officials can remedy the situation as quickly as possible.” On Saturday, company spokesman Bill Miller said the Ergon is pushing the TCEQ for answers on whether there was actually contamination.

“Inaction is bad for people in our position. The longer we sit here, the worse it looks,” he said.

More than a half-dozen lawsuits have been filed against oil refiner Valero and the privately held Flowood, Mississippi-based Ergon subsidiary, which makes paving and pavement preservation products. The Corpus Christi Caller-Times reported that several businesses and a class-action lawsuit representing all of the city’s residents allege the companies recklessly exposed business owners and residents to toxic chemicals.

Van Vleck said the city made the Ergon plant install new valves, but has not restored water service to the plant.

It’s the latest in a string of water scares for the Gulf Coast city. In May, the city issued its third boil-water advisory in a year as a precaution after nitrogen-rich runoff from rain flowed into the water system, resulting in low chlorine disinfectant levels in the water supply.

State and federal environmental records list no problems at the plant over the past five years. A TCEQ record lists an emergency response March 24 as having been closed. Clawson said he had no details, and Van Vleck said he was unaware of any incident.

Nationwide, the Environmental Protection Agency reports no current “significant violations” at Ergon facilities but shows seven receiving fines since 2010, the highest $17,200 at a Vicksburg, Mississippi, refinery.

Officials have said plenty of bottled water has been donated to help residents, and no one has turned up at hospitals with symptoms that might indicate they were sickened or burned by the chemical.