Several hundred thousand people in West Virginia remained without clean tap water for a third day Saturday following a chemical spill, and a water company executive said it could be days before uncontaminated water is flowing again.

Results of tests on water samples must consistently show that the chemical’s presence in the public water system is at or below 1 part per million, the level recommended by federal agencies, before residents can turn on their taps again, West Virginia American Water President Jeff McIntyre said Saturday at a news conference.

The company told residents in nine counties not to drink their tap water or use it to bathe or wash dishes or clothes after a foaming agent used in coal processing leaked from a Freedom Industries plant in Charleston and seeped into the Elk River. The only allowed use of the water was for flushing toilets. The order applies to about 300,000 people.

Thirty-two people sought treatment at area hospitals for symptoms such as nausea and vomiting. Of those, four were admitted to the Charleston Area Medical Center. Their conditions were not immediately disclosed, Allison Adler of the Department of Health and Human Resources said Saturday.

Federal authorities, including the Chemical Safety and Hazard Investigation Board, opened an investigation into Thursday’s spill. The board said Saturday that its investigative team is scheduled to arrive in West Virginia on Monday.

“This incident continues to impact the people of West Virginia — our goal is to find out what happened to allow a leak of such magnitude to occur and to ensure that the proper safeguards are in place to prevent a similar incident from occurring,” board Chairman Rafael Moure-Eraso said in a news release.

About 7,500 gallons of the chemical escaped from a storage tank and a containment area, said Michael Dorsey, chief of the state Department of Environmental Protection’s Homeland Security and Emergency Response group.

How much of the chemical leak reached the river was not known.

On Friday, Freedom Industries’ president issued an apology to West Virginia residents.

“We’d like to start by sincerely apologizing to the people in the affected counties of West Virginia,” Gary Southern said. “Our friends and our neighbors, this incident is extremely unfortunate, unanticipated and we are very, very sorry for the disruptions to everybody’s daily life this incident has caused.”

Some residents, including John Bonham of the Cross Lanes suburb, were willing to accept Southern’s apology.

“Yeah, I understand that stuff can happen,” said Bonham, who also works in the chemical industry. “I don’t think it’s going to get him out of legal liability. [The Occupational Safety and Health Administration] is the one they’re going to have to answer to.”

The leak was discovered Thursday morning from the bottom of the tank. Southern said the company worked all day and through the night to remove the chemical from the site.

“We have mitigated the risk, we believe, in terms of further material leaving this facility,” Southern said.

Health officials in Kanawha and Putnam counties were working to reopen restaurants, day-care centers and other facilities closed by the spill. Several facilities were inspected on Saturday after health officials approved their plans to provide water for drinking, cooking and other activities.

“We will work around the clock, 24-7, and try to open . . . as many businesses as possible in the next couple of days,” said Rahul Gupta, health officer for the Kanawha-Charleston and Putnam County boards of health.

Gov. Earl Ray Tomblin (D) said the Federal Emergency Management Agency and several companies were sending bottled water and other supplies for residents.

By Saturday morning, FEMA said it had delivered about 50 truckloads of water, or more than 250,000 gallons, to West Virginia.