The boil-water advisory led to the closure of more than 150 restaurants in the area, officials said, and water tankers were called in to deliver supplies to county agencies.
Also Thursday, county officials and Pennsylvania American said the first round of tests performed on samples taken from the system show the water has no signs of bacteria. If a second round of testing produces the same result, the advisory can be lifted as soon as Friday, company spokesman Terry M. Maenza said.
Officials said there was no evidence that the water became contaminated, but American Water customers in East Norriton, West Norriton, Lower Providence, Whitpain, Worcester, and Whitemarsh Townships were told Tuesday night to boil water as a precaution because there was an increased chance that it contained pathogens.
The utility, which has more than two million customers statewide, draws water from the Schuylkill, and officials said the recent rain stirred up sediment that affected the plant's ability to properly filter the water.
The treatment plant could not 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.
The Pennsylvania Public Utility Commission is reviewing the utility's management of the crisis, including how it notified customers, according to a spokeswoman for the commission.
Vereb noted that the rain did not cause widespread problems with other companies that draw from the river.
"This last rain that we had was a constant rain, but it was not a driving rain," Vereb said. "We've had hurricanes come through the area with no disruption to the water services."
Not everyone in the area has been without drinkable water. The Norristown-based Audubon Water Co., which serves about 2,700 residential and commercial customers, draws from wells and had no interruption.
Under a boil-water advisory, customers can use water to shower and bathe, or to do laundry. Dishes should be hand-washed with water that has been boiled first.
Madhava Mosarla, owner of the Bawarchi Indian restaurant on East Germantown Pike in East Norriton, said the restaurant was losing $900 to $1,000 each day it was closed.
"This is bad for us," he said. "We just hope and hope we can open on Saturday."
At a nearby Shop Rite, Mary Ann Brady was loading up on gallon jugs of Poland Spring Water.
"I need to rinse off some veggies for dinner," she said. "Looks like I won't be washing the dishes for a few days, but that's OK. The dishes can wait."