The D.C. Water and Sewer Authority is conducting its annual program to flush water mains throughout the city, a procedure designed to remove sediment and improve water quality.

From 10 p.m. to 6:30 a.m. Sunday through Thursday, WASA crews are opening fire hydrants in designated neighborhoods and flushing water.

The water supply to customers is not shut off during the flushing.

Customers might notice some water discoloration early in the morning. If that happens, WASA recommends that residents open the cold water tap and allow the water to flow slowly until it is clear.

Customers should not run hot water or do laundry during the flushing. If the hot water becomes discolored, WASA recommends flushing the hot water tank by opening the valve at the bottom of the tank.

The flushing program will continue through November.

These neighborhoods, with boundary streets, are scheduled for flushing the week starting Sept. 12, according to information provided by WASA:

* ANC 2D (work area in Southwest, bounded by Independence Avenue, Fourth Street, M Street and Maine Avenue).

* ANC 2A (work area in Northwest, bounded by G Street, 17th Street, Constitution Avenue and Fourth Street).

* ANC 2E (work area in Northwest, bounded by Q Street, 31st Street, M Street and 33rd Street).

* ANC 6A (work area in Southeast, bounded by R Street, Naylor Road, Good Hope Road and 18th Street).

* ANC 7E (work area in Southeast, bounded by H Street, Benning Road, Southern Avenue and Burns Street).

* ANC 7B (work area in Southeast, bounded by Good Hope Road, Naylor Road, Southern Avenue and Alabama Avenue).

* ANC 8A (work area in Southeast, bounded by Ainger Place, Alabama Avenue, Bruce Place and Stanton Road).

* ANC 8A (work area in Southeast, bounded by Minnesota Avenue, 18th Street, Valley Place and 14th Street).

* ANC 8E (work area in Southeast, bounded by Mississippi Avenue, 13th Street, Southern Avenue and Ninth Street).

* ANC 7A (work area in Southeast, bounded by C Street, Texas Avenue, Ely Place and 40th Place).

* ANC 7A (work area in Southeast, bounded by East Capitol Street, Benning Road, Ely Place and Anacostia Avenue).

* ANC 7B (work area in Southeast, bounded by Pennsylvania Avenue, Alabama Avenue and 27th Street).

* ANC 3D4 (work area in Northwest, bounded by Loughboro Road, Macomb Street and Potomac Avenue).

* ANC 3D3 (work area in Northwest, bounded by Macomb Street, 51st Place, Arizona Avenue and Potomac Avenue).

* ANC 5A (work area in Northeast, bounded by Michigan Avenue, Third Street, R Street and First Street).

* ANC 4C (work area in Northwest, bounded by Upshur Street, Rock Creek Church Road, Quincy Street and Georgia Avenue).

* ANC 3G (work area in Northwest, bounded by Military Road, Nebraska Avenue and 39th Street).

* ANC 4B (work area in Northwest, bounded by Sheridan Street, Seventh Street, Missouri Avenue and Georgia Avenue).

* ANC 4B (work area in Northwest, bounded by Sheridan Street, Third Place, Missouri Avenue and Seventh Street).

* ANC 5A (work area in Northeast, bounded by Taylor Street, 12th Street, Perry Place and Sixth Street).

For information, call the WASA Water Quality Office, 202-612-3440, 8 a.m.- 4 p.m. In an emergency, call WASA's 24-hour hotline, 202-612-3400.