There is no timeline for when 300,000 West Virginia residents can drink their tap water again, after thousands of gallons of unsafe chemicals leaked from a storage tank into the river that supplies water to households in nine counties.

FEMA distributed bottled water to residents at dozens of locations in the affected area Friday, and President Obama issued a disaster declaration for the region. Federal prosecutors announced they would investigate the chemical spill.

West Virginia American Water president Jeff McIntyre said Friday that he could not say for sure if the water his company provides is safe, and he does not yet have a timeline for when it will be drinkable again. The affected counties are all in the area around the state capitol of Charleston, including Boone, Cabell, Clay, Jackson, Kanawha, Lincoln, Logan, Putnam and Roane counties.

On Thursday afternoon, a chemical that McIntyre said his company doesn’t test for because “it isn’t supposed to be in the water,” entered the intake system on the Elk River. The substance — 4-methylcyclohexane methanol, a frothing agent used to clean coal — leaked from a 40,000 gallon tank at the Freedom Industries chemical plant, then leached through the soil into the river. It then entered the water company’s system about 2 p.m. By 4 p.m., the filtration system could no longer handle the amount of contamination in the water, McIntyre said.

McIntyre said he did not yet know how much of the chemical may have leached into the water, but a state Department of Environmental Protection spokesperson said he was “confident no more than 5,000 gallons escaped.”

“A certain amount of that got into the river,” said the DEP’s Tom Aluise. “Some of that was contained.”

No production or actual coal cleaning goes on at the Freedom Industries facility on the Elk River, where he said the company operates a tank farm for storage. The leaky tank is close to the river, Aluise said. The chemical, which is not water soluble and may look like cooking oil, will dissipate as it floats downstream, he advised.

According to a fact sheet from Fisher scientific, the chemical is harmful if swallowed, and may also be harmful if inhaled. It causes eye and skin irritation.

The spill caused a state of emergency in Kanawha and eight other counties where West Virginia American Water customers reside. Restaurants in Charleston were closed immediately, and grocery store shelves were stripped of bottled water early in the evening. Schools in the region were closed Friday.

U.S. Attorney Booth Goodwin announced Friday that his office is investigating the incident.

“Yesterday’s release of a potentially dangerous chemical into our water supply has put hundreds of thousands of West Virginians at risk, severely disrupted our region’s economy and upended people’s daily lives,” Goodwin said. “My office and other federal law enforcement authorities have opened an investigation into the circumstances surrounding the release. We will determine what caused it and take whatever action is appropriate based on the evidence we uncover.”

State Sen. Daniel Hall, a Democrat, was part way through his plate of wings at a local sports bar where he and fellow legislators had gathered to watch a game about 6:30 p.m. Hall said he got a text message about the  ban on water use, then started following local news media on Twitter. The restaurant stopped all new orders, he said.

The “No Use” order, which means that water can only be used to flush toilets and fight fires, was issued as a precaution, officials said, because they are still not sure what, if any, risk the spill poses to residents.

McIntyre said his company won’t know that until they know the health standards for the diluted chemical.

Paul Ziemkiewicz, director of the West Virginia Water Research Institute at West Virginia University, said a 3,000 gallon spill would translate to 41 milligrams per liter in the Elk River and 6 milligrams per liter in the Kanawha River, using data available now.

“Those are pretty low concentrations,” he said. “You would have to drink thousands of gallons of that water to get anywhere near a lethal dose.”

Still, he said, showering would not be a good idea, because the chemical could irritate the skin and lungs.

Details for this story were reported by The Register-Herald in Beckley, W. Va.