"We don't know that the water's not safe, but I can't say it is safe," Jeff McIntyre, president of West Virginia American Water Co, told a televised news conference. The company runs the state's largest water treatment plant.
Governor Earl Ray Tomblin declared a state of emergency for nine counties, and President Barack Obama issued an emergency declaration. The spill forced the closure of schools and businesses in the state capital.
Tests were being done on the water, McIntyre said, but he could not say when it would be declared safe for normal use.
The spill of 4-Methylcyclohexane Methanol, or Crude MCHM, a chemical used in the coal industry, occurred on Thursday (local time) on the Elk River in Charleston, West Virginia's capital and largest city, upriver from the plant run by West Virginia American Water. Water carrying this chemical has an odor like licorice or anise, McIntyre said.
The chemical is not highly lethal, but since the company does not regularly see it as a contaminant, the level that could be considered safe has yet to be quantified, McIntyre said.
A company spokeswoman said the chemical could be harmful if swallowed and could cause skin and eye irritation.
The spill originated at Freedom Industries, a Charleston company that produces specialty chemicals for the mining, steel and cement industries.
Freedom Industries President Gary Southern said in a statement the company was still determining how much Crude MCHM had been released.
"Our team has been working around the clock since the discovery to contain the leak to prevent further contamination," he said.
Emergency workers and American Water distributed water to centers around the affected area. Residents formed long lines at stores and quickly depleted inventories of bottled water.
"It's just ridiculous. There's nowhere to buy water and everywhere seems to be sold out. This isn't going to last two days," said Jaime Cook of Charleston, who was buying one of the last jugs of water at a Walmart store.
Tina May, a Charleston resident, even considered heading out of town for the weekend. "I'm not sure how long I can last without a shower. This is unbearable," she said.
The Kanawha-Charleston and the Putnam County Health Departments ordered the closure of all restaurants and schools receiving water from the West Virginia American Water company.
Schools also were closed in many counties, including Boone, Cabell, Clay, Jackson, Kanawha, Lincoln, Pocahontas and Putnam.
The spill was discovered after the West Virginia Department of Environmental Protection received a report of a strange odour on Thursday morning and visited the Freedom Industries site, where they found a leaking storage unit, a spokeswoman for Governor Tomblin said.
