Pennsylvania American Water officials said Wednesday morning that the first set of water samples overnight came back with no signs of contamination.
However, the boil water advisory will remain in effect until the results from a second round of samples are tested and are clear of contaminants.
The water company had expected the advisory to remain until at least Wednesday.
Cloudy tap water prompted the boil water advisory on Monday.
The private utility said the cause of the turbidity that prompted the precautionary advisory in 55 municipalities was a malfunctioning filter at the company’s Aldrich Purification Plant on the Monongahela River in Union Township, Washington County.
The company first reported “a spike” in turbidity at 5:30 a.m. Monday, according to the DEP’s field order.
The first samples were taken Monday night, the second round of samples Tuesday night.
Turbidity readings and total coliform tests are done in-house, and Pennsylvania American’s lab is certified by DEP.
But it may interfere with disinfection and allow for growth of viruses, bacteria, and parasites, the water company acknowledged on its website Tuesday.
Those “bugs” can cause a variety of health problems, including nausea, cramps, diarrhea and headaches, especially affecting people with compromised immune systems, the elderly and infants.