Customers in East Norriton, West Norriton, Lower Providence, Whitpain, Worcester, and Whitemarsh Townships were told Tuesday night to boil water as a precaution after some parts of the utility's system ran dry.
The Methacton School District said in a notice on its website Wednesday that it was closing some buildings early due to the problem.
The utility blamed recent rain for stirring up sediment in the Schuylkill, which affected the plant's ability to filter out the turbidity.
The treatment plant was unable to process enough water to meet demand, causing some storage tanks to empty and the system to lose pressure. When water systems lose pressure, bacteria can enter. Boiling destroys the pathogens.
Under a boil-water advisory, customers can shower and bathe as long as they don't ingest the water. Water can be used for laundry, but not dishwashers, because the water temperature does not reach the boiling point. Dishes should be hand-washed with water that has been boiled first.
The Pennsylvania Public Utility Commission is reviewing the utility's management of the crisis, including how it notified customers, said Jennifer Kocher, a spokeswoman.
The Philadelphia Water Department, which draws about half its water from the Schuylkill, said its operations had not been affected by the murky river.
Water-treatment systems purify raw river water by allowing particulates to settle in tanks before the water passes through sand filters. The water is also chemically disinfected before distribution.
Pennsylvania American is a subsidiary of American Water Works Co. of Voorhees, the nation's largest investor-owned water company.
Its Norristown plant on West Washington Street is rated to treat 18 million gallons of water a day, according to the company's website. On average, it treats about 10.5 million gallons a day.
Until the boil-water advisory is lifted, the utility has stationed water tankers at several locations for customers who bring their own containers:
Jeffersonville Fire Company, School Lane and Egypt Road.
Lower Providence Fire Company, Ridge Pike and Mount Kirk Avenue.
East Norriton Fire Company on Swede Road.
East Norriton fire station at Germantown Pike and Whitehall Road.
A Worcester Township site on Reiner Road off Spring Hill Road.