In a public notification sent out today, the City of Durham announced that its drinking water has surpassed the EPA limit for Total Haloacetic Acids (HAAs), a toxic byproduct that forms when disinfectants combine with organic matter in drinking-water supplies. According to the EPA, HAAs are carcinogenic when exposed to lab animals, and can have adverse effects on developmental and reproductive systems.
Durham's level of .064 milligrams per liter--above the required limit of .060 mg/L--is based on an "annual running average" of quarterly tests. The city's most recent quarterly test, in Feburary 2009, showed a significant decrease in HAAs. However, the City was in excess of the EPA limit for much of 2008.
Don Greeley, director of the city's Department of Water Quality, says in the release that Durham residents are "at minimal risk for harmful health effects."
To put this in perspective, you would have to drink two liters of water with this elevated level every day for 70 years to show any negative health effects. Second, my department has already been successful in significantly lowering this byproduct level in the water system.
In an interview, Department of Water Quality Deputy Director Vicki Westbrook said that high temperatures, and a reduced flow of water during the 2008 drought--factors that encourage the growth of organic material--"really did a number on us."
In the second quarter of 2008, the levels of HAAs increased by more than 1000%, from .007 mg/L to .084 mg/L, and remained above EPA required limits for the rest of the year.
In December 2008, Durham received approval from the state to change its disinfectant, from aluminum sulfate to ferric sulfate, but did not inform the public about the abnormally high levels of HAAs.
"What we’re doing is following the state guidance. Because the risk is the long-term exposure, that’s why the state gives us the guidance that they do," Westbrook said.
Westbrook added that, per state guidelines, the City gave 48-hour notice when it discovered abnormally high levels of disinfection byproducts such as HAAs at specific locations. In February 2008 alone, eight locations--including a City Hall water fountain--were in violation of the EPA limits.
View the City Q&A's on water safety here.