The Census Bureau last week reported what many homeowners in this area already know: Damp basements are the bane of American housing.

In a national survey, the bureau found that water leakage in basements was the most commonly reported structural defect. Signs of water leakage were cited by 6 million owners, a fourth of those surveyed, and 17 percent of the renters in buildings with basements.

The second-most common complaint was about mice or rats, followed by street noise, crime, heating equipment breakdowns, lack of street lights, public transportation and outdoor recreational facilities.

The survey covered occupants' attitudes about their neighborhoods and the services provided there as well as indicators of housing quality such as plumbing, kitchen facilities and mechanical equipment.

Claxton Walker, a home inspector in this area, says damp basements are a growing problem in part because homeowners are making more use of that area of the house.

Ranking his own list of consumer concerns that discourage buyers, Walker, who is president of an inspection firm, cited "first impressions," water leakage, termites and old heating systems.

"There's no question that water in the structure scares them off," he said. "And it's because in most cases, people are getting more use out of basements as recreation, family and game rooms."

It's not shoddy workmanship but a more difficult and mucky soil and the fact that roof lines are lower," he said.

Water leakage is a particular problem here because of the humid climate, a "well-drained" soil that absorbs water quickly from the surface and more underground water activity, according to Alvin Sacks, one of Walker's associates.

Further, Walker noted that another cause for water leakage is that most of the newer houses have basements that are deeper than those in older frame homes, which were built higher off the ground.

New houses alsp have a problem with "reverse grading," which occurs about five years after construction. Fill dirt around the foundation begins to settle then, resulting in water-collecting holes.

Dirt is built up about six inches around the foundations of new houses to create a grade. Since the soil is not naturally compacted, it needs to be built up again to create a run-off.

Walker said malfunctioning gutters and the lack of run-off splash blocks near the downspout also aggravates water leakage.

Telltale signs of water problems are mildew and efflorescence, a white powder residue on walls caused by minerals seeping from the mortar.

As a result of the water and humidity, carpets buckle, tile curls, wood is stained and stored household belongings are ruined.

Another problem area that homebuyers look at is the age of the furnace and water heater, Walker said.

"But they should not be as concerned with the possibility of replacing a furnace at $1,000 to $1,500 as with the age of the galvanized steel water supply pipes," he added. Pipes will corrode and build up deposits inside after about 45 years, he said.

Replacing the pipes means a complete plumbing, plastering and painting job throughout the entire house.

According to the Census Bureau survey, 15 percent of homeowners surveyed cited problems with mice and rats and 23 percent rated nearby recreational facilities as unsatisfactory.

The incident of high neighborhood crime was reported by 15 percent of the homeowners and 21 percent of the renders. Breakdowns in heating equipment were reported by 6 percent or 43.8 million homeowners, and by 10 percent of the renters. CAPTION: Illustration 1, CLICK; Illustration 2, DRIP - DRIP; Illustration 3, CLUNK - BUMP; Illustration 4, SQUISH - SQUISH - SQUISH; Illustration 5, SQUISH - DRIP - SQUISH - DIP...SQUEEK!, By William T. Coulter for The Washington Post