West Virginia officials told residents Monday to flush out their home water systems before using the tap water again, and the ban on the water persists in some places. Tests at the affected water treatment plant show almost no contamination. However, some toxicologists say, the spill shows how little is known about many chemicals in common use.
Some 300,000 water customers have been under a ban since a chemical spill last Thursday. The ban on using tap water was lifted in at least three affected areas Monday.