If the facts are really as they were presented in The Post's story "Couple Gets Raw Deal on Sewage" {Metro, July 24}, the bum cards the reporter has dealt the Washington Suburban Sanitary Commission (WSSC) are what's really raw.

The Post's reporter fails to mention that Maryland law, which was strongly supported in Annapolis by the WSSC and has been in effect since about 1972, requires that insurance agents writing (and renewing) homeowners' insurance policies in the state advise their customers of the availability of coverage -- as a policy add-on -- for damage from backups through sewers or drains. This notification requirement is designed to put the insured household on notice that it is not covered unless an additional premium is paid for the protection; but, with this advice in hand, the resident of a house with a finished basement containing drains, lavatory facilities and valuable furnishings would be foolish not to buy sewer back-up coverage.

After all, sewers and drains, like other public utilities and many other consumer goods and services, cannot be guaranteed to be trouble-free; and anyone who doesn't treat a basement area as a vulnerable spot for damage from sewer stoppage, water pipe breakage, storm-water penetration or leakage from a worn-out hot-water heater is risking a loss of the type experienced by the Martin family in Olney.

A check of the WSSC's suburban Maryland plumbing code would show that basement drains have not been permitted in new development units for more than a decade; so, unless the area involved in the Martins' "four-year-old" home is not technically a basement and has a drain, installation of a back-water valve might not be feasible. I doubt if such an installation was suggested by the WSSC.

Although the article heaps most of the blame for the Martins' loss on the WSSC's doorstep, it probably doesn't belong there.

ARTHUR P. BRIGHAM Silver Spring