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. 19, 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 K Street, 24th Street, E Street and 27th Street.

* ANC 2E (work area in Northwest, bounded by P Street, 44th Street, Potomac Avenue and Elliot Street).

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

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

* ANC 7B (work area in Southeast, bounded by Pennsylvania Avenue, 29th Street, Naylor Road and 27th Street).

* ANC 8A (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 and Stanton Road).

* ANC 8A (work area in Southeast, bounded by Morris Road, 18th Place-Stanton Road, Alabama Avenue and 13th Street).

* ANC 6C (work area in Southeast, bounded by Minnesota Avenue, 18th Street, Valley Place and 14th Street).

* ANC 6C (work area in Southeast, bounded by W Street, Hunter Place, Howard Road and Martin Luther King Avenue).

* ANC 8A (work area in Southeast, bounded by Howard Road, Stanton Road, Sheridan Road and Wade Road).

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

* ANC 8E (work area in Southeast, bounded by Chesapeake Street, Ninth Street, Southern Avenue and Fourth Street).

* ANC 8C (work area bounded by Atlantic Street SE and SW, First Street SE, Galveston Street and Martin Luther King Avenue SE).

* 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 7A (work area in Southeast, bounded by East Capitol Street, 51st Street, C Street and Benning Road).

* ANC 3D (work area in Northwest, bounded by Arizona Avenue, Chain Bridge Road and Potomac Avenue).

* ANC 3D (work area in Northwest, bounded by Ashby Street, Hoban Road, Salem Lane and Canal Road).

* ANC 3D (work area in Northwest, bounded by Reservoir Road, 44th Street, P Sreet and Canal Road).

* ANC 5A, (work area in Northeast, bounded by Randolph Street, 14th Street, Otis Street and Michigan Avenue).

* ANC 5A (work area in Northeast, bounded by Otis Street, 13th Street, Hamilton Street and Ninth Street).

* ANC 5A (work area in Northeast, bounded by Hamlin Street, 13th Street, Rhode Island Avenue and Ninth Street).

* ANC 4C (work area in Northwest, bounded by Decatur Street, Illinois Avenue, Upshur Street and Georgia Avenue).

* ANC 4D (work area in Northeast, bounded by Delafield Street, Fort Totten Drive, Taylor Street and North Capitol Street).

* ANC 4D (work area in Northwest, bounded by Farragut Street, New Hampshire Avenue, Allison Street and Illinois Avenue).

* ANC 3F (work area in Northwest, bounded by Chesterfield Place, Broad Branch Road, Yuma Street and Connecticut Avenue).

* ANC 3F (work area in Northwest, bounded by Albemarle Street, Connecticut Avenue, Upton Street and Reno Road).

* ANC 3F (work area in Northwest, bounded by Yuma Street, Linnean Avenue, Porter Street and Wisconsin Avenue).

* ANC 3G (work area in Northwest, bounded by McKinley Street, 29th Street, Broad Branch Road and Nebraska Avenue).

* ANC 3G (work area in Northwest, bounded by Nebraska Avenue, Oregon Avenue, Northhampton Street and 32nd Street).

* ANC 3G (work area in Northwest, bounded by Tennyson Street, Oregon Avenue, Jenifer Street and 32nd Street).

* ANC 4B (work area in Northwest, bounded by Sheridan Street, Blair Road, Longfellow Street and Third Place).

* ANC 4B (work area in Northeast, bounded by Kansas Avenue, Eastern Avenue, Nicholson Street and Chillum Place).

* ANC 4B (work area in Northwest, bounded by Aspen Street, Georgia Avenue, Sheridan Street and 16th 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.