Both the Centers for Disease Control and Prevention and the U.S. Environmental Protection Agency have said that drinking water is safe when levels of the chemical fall to 1 part per million or below, said Jeff McIntyre, president of West Virginia American Water.
"Currently there are four laboratories testing water samples from the river. When levels fall below 1 ppm the Do Not Use order can be removed," he said.
Initial testing found a level of 3 ppm, said Maj. Gen. James Hoyer of the West Virginia National Guard.
First, however, the entire water system will need to be flushed out, a process that could take several days, he said. It is a difficult process because of the hilly nature of West Virginia and the large number of storage tanks required to keep the water system working, McIntyre said.
"We have 100 water storage tanks and 1,700 miles of pipe" to flush, he said.
Five people have been admitted to the hospital and 24 have sought treatment for symptoms such as nausea and vomiting, said Allison Adler of the West Virginia Department of Health and Human Resources at a press conference Saturday in Charleston.
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The Federal Emergency Management Agency has already brought in 4.1 million liters of water to the area and another 800,000 liters are on their way, said Homeland Security and Emergency Management Director Jimmy Gianato, director of the West Virginia Division of Homeland Security.
The water that comes out of the taps is "gross," said Jane Haley, 48, in Charleston. "It's hard to describe how bad it smells."
Saturday was rainy "so I put out two coolers out and filled them up with rainwater. I heated the water up on (the) stove and used it to wash my hair," she said.
Others were more direct.
"I was laying in bed this morning and I heard the rain and I thought, 'Thank God,' " said Debbie Stevens, 54.
The Charleston resident grabbed her shampoo and conditioner and went outside to stand in her pajamas under a leaky gutter that was pouring rainwater.
"I washed my hair and then I came in and used my wet pajamas take a horse bath," she said.
The primary component in the foaming agent that leaked is the chemical 4-methylcyclohexane methanol.
Engineers have placed booms in the Elk River to catch as much of the chemical as possible that might be leaking from the ground near the tank, said Mike Dorsey with the West Virginia Department of Environmental Protection.
"To the best of our knowledge there's no more material getting into the river," he said at the Saturday news conference. The tank itself is no longer leaking, he said.
However, once the chemical gets into the main body of the river, "there's not much you can do except let it flush through," Dorsey said.
The chemical disperses in the water and becomes more diluted, a process that "is happening in real time," he said.
The Kanawha River eventually feeds into the Ohio River, but the dilution factor makes Dorsey unconcerned about people who get their water from the Ohio.
"By the time you get to the Kanawha and then the Ohio, I don't see how it could be an issue for people downstream," he said.
Small businesses are reeling under the shutdown.
"We're not hearing anything from the state, that's what's scary," said Tammi Ray, 54, who owns Handiman Car Wash in Charleston. "This is our busy season. Up to Friday, we had done about 3,100 cars this week. People don't want the salt on their cars so they come in to get them cleaned up."
On Thursday night, she closed down her operation, putting her 12 employees out of work. "I can't risk it, it's a health hazard for my workers," she said.
To aid businesses, the state and local health departments are allowing those with portable water systems to reopen. The business must first submit a plan to the local health department, which will review and approve it and then do a site visit.