February 25, 2000

Phosphorous Not Used In MWRA Drinking Water

In an effort to reduce the amount of lead and copper that can leach into drinking water from homes with lead or copper pipes or pipes with lead solder, MWRA in 1996 modified the chemistry of its water to make it less corrosive. By adjusting the pH and alkalinity of the water, MWRA has been able to dramatically reduce lead levels in "at risk" homes throughout its service system.

Adjusting the water’s chemistry however, was not the only solution considered. Another common practice in the drinking water industry to reduce the levels of lead and copper in drinking water is the addition of orthophosphates or phosphorous to coat the pipes. Though effective, the phosphorous can raise environmental questions. By relying on pH and alkalinity adjustments, MWRA has avoided these problems.

A Boston Globe editorial published today, "Phosphorous Dilemma," highlights the inherent risk that comes along with using phosphorous.

"Phosphorous and its compounds," the editorial states, "can also produce damaging growth of algae and plant life in streams and ponds. . . . Trouble came to light recently when West Hartford, Connecticut discovered that a pond was producing unusual quantities of plant life because of a water main break. The vegetation can deplete oxygen in the water, harming fish and other aquatic life."