Some Montgomery County residents can expect temporary water discoloration this week as a result of the Washington Suburban Sanitary Commission's water main flushing program.

The systematic flushing program has been undertaken to clean out the build-up of iron and manganese sediment that has accumulated in the WSSC Montgomery County distribution system during the past two severe winters. The sediment build-up has caused some widespread water discoloration in the county. The WSSC said the sediment is harmless, but aesthetically objectionable.

The flushing project is designed to reduce the possibility of widespread water discoloration in the future and involves running water through fire hydrants to clear out the sediment. The project will cover the WSSC network of more than l,500 miles of water mains in the county from now through November. More than half the ll,140 fire hydrants in the county are expected to be opened.

The overall cost of the project is expected to be $163,000 to $193,000, according to the WSSC.

The WSSC has suggested that customers in the local areas of hydrant openings prepare for the four - or five-hour inconvenience of discoloration by taking these steps in advance: Store some clear water from the taps in sealed containers. When flushing is about to begin in your neighborhood, draw additional water for household use in bathtubs, sinks, laundry tubs and pots and pans. When it's possible, postpone laundering and dishwashing will automatic machines while the clushing is going on. At the first sign of discoloration of water coming from your tap, don't do any laundering, since the iron-manganese sediment can stain clothes.

Crews are scheduled to be in the following areas this week: Today - Bells Mill Village and Windsor Hills in the daytime and Inverness Forest in the evening; Friday - Inverness Forest and part of McAuley Park in the daytime, with no evening flushing; Saturday - no flushing; Sunday - evening flushing in Windsor Hills, Coat Woods and Fox Hill; Monday - Fox Hill, Lake Normandy, Oldfield and Willowbrook in the daytime and Willowbrook in the evening, and Tuesday - no flushing until July.