New Federal Arsenic Standards for Drinking Water Go Into Effect

January 25, 2006

New federal drinking water standards designed to lower the levels of arsenic in drinking water took effect Jan. 23 for Pennsylvania's public water systems, Environmental Protection Secretary Kathleen A. McGinty said. The federal law lowers the maximum contaminant level (MCL) for arsenic from 0.050 milligrams per liter (mg/L), or 50 parts per billion, to 0.010 mg/L, or 10 parts per billion. Pennsylvania's Department of Environmental Protection (DEP) incorporates by reference federal MCLs as state MCLs.

The U.S. Environmental Protection Agency (EPA) adopted the new standard for arsenic in drinking water Jan. 22, 2001. The rule became effective Feb. 22, 2002, and compliance became mandatory Jan. 23, 2006.

DEP said it worked with community water suppliers and non-transient, non- community public water suppliers - those that serve water to at least 25 of the same people for more than six months in a year, but not year-round - to help bring their operations into compliance ahead of the effective date. The department sent letters to all public water system operators in July 2005 informing them of the change, and the systems were alerted again through a DEP media campaign in October.

DEP officials were in direct contact with systems identified as having arsenic levels above 0.010 mg/L in past monitoring. According to historical information, about 90 of a total of 3,340 systems (or about 3 percent) have arsenic levels above 0.010 mg/L.

Initial compliance monitoring for arsenic will begin immediately for the new MCL. State regulations require water systems in violation of the MCL to issue public notification and conduct more frequent monitoring as interim measures until treatment is provided to reduce the arsenic levels or a new source is brought on line.

Source: Department of Environmental Protection (DEP).