No basement is completely free of moisture. There is no such thing as a completely dry basement. This doesn’t mean that you have to spend your days waiting for the cellar to fill with water. It simply means that the basement, more than any other area of the house, is affected by moisture, and you have to consider the most efficient way to control any dampness before you spend thousands of dollars turning the space into what may turn out to be an indoor swimming pool.
For example, air-conditioning ductwork in basements “sweats” when cold metal comes into contact with damper air. Rather than having water dripping from the ducts onto the rug, a dehumidifier properly sized for the space will keep the basement drier.
Of course, you’ll need to find the proper humidity setting and empty the dehumidifier bucket when it’s full, but that’s the price you pay for a drier basement. The size you buy is based on water removal from a certain number of square feet over 24 hours.
If water gets into the basement during heavy rains, you might solve the problem by cleaning gutters so the water will not be diverted to portions of the foundation that are more susceptible to leaks. You also should be certain that areas around the foundation are graded properly.