Gretna officials on Friday lifted a boil-water advisory they had issued a day earlier. They said they had concluded that fears about bacteria in the municipal water supply were unfounded.

Follow-up inspections showed that Gretna’s water system was never contaminated despite an earlier test suggesting that E. coli and other coliform bacteria were present in the water.

Residents were notified at 1:45 p.m. Friday that it was safe to use tap water again, City Attorney Mark Morgan said.

The state Department of Health and Hospitals collected water samples from Gretna on Wednesday, and results Thursday morning showed the presence of E. coli and other bacteria.

The city was alerted about the results at 9:30 a.m. Thursday, and two hours later, Mayor Belinda Constant’s office advised residents to boil water before drinking it or using it to bathe, make ice, wash food, shave or brush their teeth.

The state conducted another round of tests Thursday and determined Friday there was no contamination in Gretna’s water supply, Morgan said.

“That is an indication that the issue was with the testing or collection of the samples and not the water system,” Morgan said. “The water system was never contaminated.”

The boil-water advisory affected only residents with the ZIP code 70053. It did not apply to Timberlane Estates and unincorporated areas on the West Bank of Jefferson Parish. Those areas are supplied by a separate water system.

Coliform bacteria, including E. coli, can give people diarrhea, cramps, nausea and headaches. Infants, young children and people with weak immune systems are especially vulnerable to the bacteria, which can appear in water supplies that have been contaminated by human or animal waste.