The District of Columbia Department of Health has issued the following advisory – targeted especially for schools and childcare facilities – concerning flushing interior plumbing systems if water has not been used for an extended period of time:

In homes, schools and offices that have been closed for a long period of time, especially during the hot summer months, bacteria can multiply rapidly in unused and seldom used water lines, and attach to the inside surfaces of pipes. In addition, certain bacteria can increase the level of nitrite in the water which, in turn, increases the potential for bacteria growth. Regular flushing will replace stagnant water with fresh drinking water, which is less likely to contain bacteria, nitrite or other contaminants. Flushing will also help to eliminate the odors, stale taste and discoloration of stagnant water.

For more information, you may contact the Disctrict Department of Health at (202) 442-9155 or the District of Columbia Water and Sewer Authority (WASA) at (202) 787-2200. Guidelines on measures that can be taken to ensure safe drinking water are available from the Safe Drinking Water Hotline (800-426-4791) and on the EPA Web site.