For Immediate Release: March 26, 1999
Contact: David Gilmartin, Public Affairs, 617-788-1183

Arsenic Information: Routine MWRA Drinking Water Test Levels Are Far Below New Standard Proposed By National Research Council

The Massachusetts Water Resources Authority today posted information on its website regarding arsenic levels in drinking water in response to a March 24th Boston Globe story (Panel Says U.S. Is Lax On Arsenic In Water), reporting that the National Research Council recommended that the EPA's 37 year old not-to exceed standard of 50 parts per billion (ppb) of arsenic in drinking water should be brought into line with the World Health Organization's standard of 10 ppb. The piece unfortunately did not contain information on arsenic levels in the Boston area.

Recently, the National Research Council, an arm of the National Academy of Sciences, asked the federal government to lower its permissible arsenic limit, which is presently set at 50 parts per billion (ppb). The MWRA's tests have shown that its water contains an arsenic level of less than 0.8 ppb and have never risen above 1.66 ppb. Both figures are well below both existing and proposed limits. While arsenic is a naturally occurring element that is present in many places, significant amounts have been shown to be harmful.

Arsenic is one of the many possible contaminants the MWRA regularly tests for in accordance with state and federal regulations. Monthly tests are made at four locations to determine levels of this substance that occurs at trace levels throughout the environment. In the last year most of the test results for arsenic have been "below detection limit" of .8 ppb, less than one tenth of the new and more restrictive upper limit that has been urged by the National Research Council. Of the few tests in which arsenic was detected, the highest recorded value was 1.66 ppb, less than one-sixth of the strict proposed standard.

The MWRA believes that testing information on MWRA drinking water is important to its customers. The arsenic testing results, together with testing results for many other substances of possible concern for water supplies, are made available in monthly reports mailed to public health officials and others. These reports are also available online at


Back to What's News