"At the governor's request, we're developing some proposals as to how we're going to more properly regulate these facilities in order to minimize the risk of a spill," Huffman said.
McIntyre said testing teams will continue to monitor the chemical's levels, not only in the Elk River, but also the Kanawha and Ohio rivers. The company's Huntington treatment plant is preparing for potential effects of the leak as it moves downstream, he said.
Another chemical spill occurred along the Ohio River in Belpre, Ohio, last week. That spill was 120 miles upstream from the Huntington plant, according to McIntyre.
Huffman said sewer and sanitary boards throughout the affected area have been made aware of the flushing and are preparing for an increase in flow through those systems.
Customers with questions about septic tanks should contact their local sanitary boards or health departments with those questions, Huffman said.
Those who need assistance flushing their systems are directed to call their local emergency management offices.
Fourteen people were hospitalized with non-life-threatening symptoms that could be related to the chemical leak, officials said.
Crude MCHM, a coal-processing chemical that is actually 4-methylcyclohexanemethanol, leaked from a Freedom Industries facility into the Elk River on Thursday morning. Residents in parts of nine counties have been advised not to drink water or use the water in any capacity except for flushing toilets and fighting fires since then.
Officials said that more than 90 percent of tests show the MCHM levels are now "well below the health risk level."
But a timeline for when the water will be usable is still undetermined, McIntyre said.
"It's hard to predict because it depends on the behavior of the people. If people don't follow the instructions ... it will go longer," he said. "It could still be days before we have the entire system cleared. It's a very large, complex system."
The black licorice odor associated with the chemical may still be prevalent, but does not mean people should flush past the recommended amount, officials said.
State Superintendent of Schools Jim Phares said that schools will reopen when it is confirmed that all systems are safe, and that there will be no rush to get back to class.
"We want to add assurances that every child, all children, will be safe when they return to school," Phares said.
Restaurants in Charleston began reopening their doors to customers upon news of the end of the do-not-use water advisory Monday afternoon.
Meena Anada, co-owner of Little India on East Washington Street, said she hired a contractor to flush out the restaurant's water pipes. Anada said she would still serve customers bottled water until she felt comfortable using the faucet again.
An employee at Pies and Pints on Capitol Street said the restaurant was busy with customers Monday night. The restaurant flushed out its water pipes early Monday afternoon and is serving water from the faucets.
At the Charleston Town Center Mall, marketing director Lisa McCracken said all restaurants but three would reopen Tuesday morning. Those three restaurants, Dairy Queen, Five Guys Burgers and Fries and Sakkio Japan, would be inspected by the Kanawha Health Department sometime Tuesday.