Aqua Pennsylvania has lifted a boil-water alert for customers in two Chester County towns, but is still asking thousands of suburban customers to conserve drinking water until it restores a flood-damaged treatment plant to full service.

The Bryn Mawr water company on Friday night alerted customers in East Whiteland and Charlestown Townships that they no longer needed to boil water, an advisory put in effect after floodwaters knocked out the system’s largest treatment plant on Sept. 1. That outage reduced supplies of drinking water to hundreds of thousands of suburban customers.

The company, a subsidiary of Essential Utilities Inc., said Friday it has restored partial operations at its Pickering West water treatment facility in Schuylkill Township. But Aqua said “it may take days or weeks for normal water supply levels to be achieved,” and “strongly encourages” its customers in the Philadelphia suburbs to reduce water consumption until further notice.

Aqua spent $20 million a decade ago to improve its two Pickering water treatment plants, including increasing the height of floodwalls to protect its largest treatment plant from a 100-year flood. But record floods on Sept. 1 crested the walls, inundating the plant’s interior with up to 6 feet of water and debris, destroying electrical and computer systems.

The Pickering West plant, located near the confluence of Pickering Creek and the Schuylkill near Phoenixville, supplies up to 40% of the drinking water for its suburban system. The company was able to maintain water pressure on its system by producing more water from other treatment plants located throughout its system.

Aqua has 372,000 water customers in Chester, Delaware, Montgomery and Bucks Counties and serves an estimated population of about 1 million in Philadelphia’s collar counties.

The company on Friday thanked customers for their conservation efforts. Marc Lucca, president of Aqua Pennsylvania, asked them to continue to curtail nonessential water usage “for a little while longer as we work to get back to normal supply levels and full operations.”

Aqua’s top tips for conservation: Turn off water while brushing teeth and shaving; take shorter showers; only run washers and dishwashers with full loads; and turn off automatic lawn sprinklers.