Nine West Virginia counties are in a state of emergency following Thursday's chemical spill in the Elk River in Charleston, the state's capital.
FEMA and the West Virginia National Guard are now set to help distribute water to about 300,000 people who are unable to use the water in their homes.
The problem began when a storage tank at Freedom Industries started leaking chemicals used to process coal. The spill inundated the river and a nearby water treatment plant.
The chemical spill has forced many schools, restaurants, and health facilities to close.
"I don't know if the water is not safe," water company president Jeff McIntyre said. "Until we get out and flush the actual system and do more testing, we can't say how long this (advisory) will last at this time."