Pa. American lifts boil water alert for parts of Chester, Lancaster Counties.

Pennsylvania American Water on Monday lifted a boil water advisory for 14,500 customers in parts of Chester and Lancaster Counties after restoring water purification levels to normal.

The company on Saturday advised customers served by its Rock Run Water Treatment Plant near Coatesville that water produced at the plant had “lower-than-normal chlorine residuals” and advised them it should be boiled before consumption.

The notice applied to customers in Pennsylvania American’s Coatesville system, which includes the City of Coatesville, Parkesburg, and South Coatesville, and portions of Atglen, Caln, East Fallowfield, Highland, Sadsbury, Valley, West Caln, and West Sadsbury Townships, Chester County. Residents in the Borough of Quarryville and Bart, Colerain, Eden, and Sadsbury Townships, in Lancaster County, were also impacted.

Tests on water Sunday indicated that levels of chorine, which is added to water to kill harmful bacteria, had returned to acceptable levels. During the episode, customers were advised to boil water for at least a minute and letting it cool before using it for cooking or drinking.

The cause of the problem is under investigation. The Rock Run Water Treatment Plant, on Water Works Road next to Coatesville Reservoir, was undergoing system upgrades before the alert was issued, a spokesperson said.