WASHINGTON — Beginning on Feb. 1, and continuing through May 17, 2010, the Washington Aqueduct will temporarily change the disinfectant used in its water treatment process from chloramine to chlorine.

The change is part of a joint annual program to keep water pipes clean and free of potentially harmful bacteria. The Washington Aqueduct is the organization responsible for treating the water for the District of Columbia, Arlington County, Va., and Falls Church City, Va., including portions of Fairfax County served by Falls Church City.

A temporary switch to chlorine is a standard water treatment practice. The short-term use of chlorine is important for maintaining high water quality throughout the year, but will temporarily increase disinfection byproducts during this period. Disinfection byproducts are formed when chlorine reacts with natural material found in the Potomac River, and may be associated with reproductive and long-term health effects such as cancer. Chloramine is used to disinfect the water most of the year to limit long-term exposure and reduce disinfection byproduct levels.

Individuals and business owners who take special precautions to remove chloramine from tap water, such as dialysis centers, medical facilities and aquatic pet owners, should continue to take the same precautions during the temporary switch to chlorine. Most methods for removing chloramine from tap water are effective in removing chlorine. As always, the drinking water will be regularly monitored to verify that it meets federal standards.

During this time, people may notice a slight change in the taste and smell of their drinking water. Any changes in water color should be temporary. Simply run the cold water from the faucet until the water is clear. In the unlikely event that the water remains discolored and cloudy, contact the DC WASA Water Quality Division at 202-612-3440 (Monday to Friday, 8:00 a.m. to 4:30 p.m.) or 202-612-3400 (24-hour).