Durham water customers are going to be getting a public notice of bad stuff in their water, but not to worry — according to city authorities.
"We think now we've licked the problem," water director Don Greeley said this afternoon.
The problem was high levels of haloacetic acids and trihalomethanes in water coming through the city's two treatment plants in May and September last year.
Those chemicals are byproducts of Durham's treatment process, and a result of excess plant growth in stream and reservoir beds during the 2007-'08 drought.
The water is safe to drink, said Greeley and deputy City Manager Ted Voorhees. Consuming high amounts of haloacetic acid over "a lifetime" can lead to liver problems, though.
Contaminant levels returned to normally low levels in December and February, Greeley said. However, the spikes last year raised the "running average" level above acceptable limits.
That, by federal law, requires public notice, Voorhees said. Besides press releases and notices in water bills, the city will be posting frequently asked questions on its Web site and including information in the water department's annual report.
Durham has never exceeded acceptable levels of HAA and THM in its running average before. The running average is a combination of four consecutive quarterly test results.
Durham was using aluminum sulfate in its water-treatment process. Excess carbon in the reservoirs, due to plant decay, reacted with the aluminum sulfate to form haloacetic acids and trihalomethanes, Greeley said.
In December, Durham switched from alumninum sulfate to ferric sulfate, and the contaminant levels immediately dropped to normal levels, according to Greeley.
"We're having great results," he said.