CNN — (CNN) -- A few thousand more West Virginians learned they could use their tap water Tuesday morning, nearly a week after a chemical leak tainted the supply for them and hundreds of thousands of others.
A "do not use" order was lifted for yet another zone Tuesday -- the Southridge/Southside area near Charleston -- bringing to about 35,000 the number of customers now free to use the water after first flushing their plumbing, the West Virginia American Water Co. said.
But nearly 90% of the 300,000 people initially prohibited from using their taps still are waiting for the all-clear.
The state put water restrictions into effect in nine counties Thursday after thousands of gallons of 4-methylcyclohexane methanol poured out of a storage facility into the Elk River. The licorice-scented chemical, typically used to clean coal, got into the water supply, resulting in people being told not to drink, cook or wash with water from their own taps.
The spill left some residents scrambling for bottled water to wash their hands, brush their teeth and cook. Without safe water, schools and many businesses were forced to close.
It also led to preventive measures in at least one major city outside West Virginia. The Greater Cincinnati Water Works, which serves that Ohio city and parts of four counties in Ohio and Kentucky, will temporarily stop taking water from the Ohio River as a precautionary measure, allowing water that might contain traces of the chemical to pass the city, company spokeswoman Michele Ralston said Tuesday.
West Virginia's Elk River, where the spill happened, is a tributary of the Kanawha River, which feeds into the Ohio River.
The Cincinnati utility is sampling the Ohio River water and so far hasn't detected anything out of the ordinary, Ralston said. The move will not disrupt customers' water supply because the company has a two-day reserve supply and a groundwater plant that can provide even more treated water, she said.