AUSTIN, Texas — The smell and taste of water in Central and South Austin should return to normal Friday after the city received multiple reports of an unusual odor Thursday.

Based on routine testing and staff analysis, Austin Water said it believes the odor was likely caused by the presence of zebra mussels in a raw water pipeline at the Ullrich Water Treatment Plant in west Austin. 

That pipeline was put back into service on Feb. 6 after being taken out of service over the past two weeks for repairs.

"This was the first time we inadvertently found that, when we were doing construction, to have about two inches of zebra mussels attached to the pipeline," Rick Cornado, the assistant director of operations at Austin Water, said.

Cornado believes the zebra mussels attached themselves to the 72-inch pipeline during its repairs. It's possible they began to decay and secreted a compound into the water that affected its smell and taste.

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Austin Water will be treating the water with activated carbon to help with the issue. Activated carbon, which comes in a powdered form, is often used to help with taste and odor occurrences. Crews will also be flushing water lines in the affected areas.

Some Austin Water customers said their water smelled like sewage. Others, like downtown resident Forrest Preece, thought it smelled like rotten eggs.

"It was not that awful. We just put off taking our shower 'til this afternoon. It kinda cleared up," Preece said.

Austin Water expects the odor issues to be resolved by Friday and said the water is safe to consume.

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