Water supplied to Portsmouth residents has exceeded the federal EPA standard for trihalomethanes (TTHMs) for the past year, according to a statement released to media today by the Portsmouth Water and Fire District (PWFD). The EPA standard is 80 parts per billion (ppb) for an annual running average, and the Portsmouth water came in at 89.2 ppb.

TTHMs, according to the EPA web site, are "a group of four chemicals that are formed along with other disinfection byproducts when chlorine or other disinfectants used to control microbial contaminants in drinking water react with naturally occurring organic and inorganic matter in water."

According to PWFD, the level does not constitute an emergency and no action by customers is required, but it has triggered a notification requirement. PWFD customers will receive notice by mail from the district within the next month.

The new water treatment plant under construction on West Main Road will incorporate advanced processes to ensure compliance with drinking water standards, the PWFD said, and is scheduled to become operational before the end of the year.

Read more about TTHMs on the EPA site, or download the full press release here.

Editorial note: Written from a press release.