For basement moisture to be a serious problem, there doesn't have to be a foot of floodwater covering the floor. Investigate any dampness, even if it appears benign. After all, water enters the basement in myriad subtle ways, and its ill effects take hold, not suddenly, but over time. Before you can seek a solution, you must first determine the source of the moisture. Once you know where it's coming from, you can take the appropriate steps to get rid of it.