Prospective homeowners should rank the possibility of a wet basement high on their checklists when investigating a new or resale home.

It is important to find out if the basement has water problems and how severe they are. Here are some points to check:

The general area. be aware of the names of real estate developments like "Willow Run" or "Babbling Brook Estates." Most counties have maps of soil conditions and flood plains.

The terrain. Is the house at the top of the street or at the bottom? On the low side of the street or the high side? Again, the probability of water is more likely in the low sections.

Grading. how well is the yard graded to the property lines and street? Has the original backfill area adjacent to the walls of the house been raised since construction or has the grade sunk to yield no slope, or even a slope back towards the house? If so, be alerted for water problems inside.

Of all the factors involved in wet basements, the most common is a flat or a reverse grade next to the foundation walls. A slope of at least one inch to one foot for a distance of six feet or more should be established and maintained. Water must drain far enough away that the capillary pumping action of the adjacent, higher, drier earth will continue wo create dryness around the walls.

Depth of the basement in the ground. It makes a world of difference. Many old houses with high front porches have no basement waterproofing, yet rarely leak, simply because they are only in the ground two to three feet.

Properly functioning gutters and down-spouts. Check for stopped-up gutters, overflow, sag and size. Any of these malfunctions will dump another 1,000 or so square feet of roof water next to the basement walls.

A basement is little more than a hole in the ground. Given complete earth saturation, any basement will take on water. The down-spouts must not dump water on the ground in the vicinity of the walls. If spout discharge is on the surface, use three-foot splash blocks and even a few additional stepping stones.

If the water is piped underground, it must be in a watertight pipe fr at least six feet. The water must run free. Probe the boot. Look for erosion signs of water backing up. If dry wells are used, they should be at least 15 feet away (depending on soil percolation) or water flow may work in reverse - collecting ground seepage in the pit and draining back to the bigger "hole" - the basement.

Interior problems. First, sniff for damp odors. Ask about ventilation in the basement and determine if the house has been shut for a long period of time.

Look for rings or efforescence on block walls. White, powdery mineral residue will indicate saturation of the outside earth. The walls might be damp, usually in the corners, because that's where the spouts are. Observe woodwork at the base boards and the plates, particularly under the stairs, but don't be concerned too much with one water ring. One wetting from a burst pipe or appliance overflow will cause a water mark.

Be alarmed, however, if you find blackness, rot or heavy rusting of the nails. If walls have been recently panelled, and you suspect cover-up, look further. For example, remove the cover plate from a wall receptacle and inspect the rusting in the box.

Continual wetting or prolonged dampness. It causes asphalt or vinyl asbestos tile to puff and crust at the joints. You often see this around the washer-dryer area. These signs cannot be passed off as one wetting - one unusual circumstance of nature. It means there is water or dampness continually. Next to low grades and improper spout discharge, this sign is most significant.

Staining or rust under appliances, stairways, or other places that may not have been recently painted or refloored.

Recommendations for the alleviation of basement water problems should start with the simplest measures, such as proper grading, gutters and spouts. Then, if more seems needed, drain tile and sump-pump systems, excavation and waterproofing may be necessary. Choose the cure, not the palliative: Keep the water away, instead of collecting it and pumping it out. Claxton Walker is head of a local home inspection firm.