To eliminate mold/mildew growth, stop water leaks, keep the relative humidity below 50%RH. Get a %RH meter from a hardware store, or wal-mart $15. In green grass climates, you need a adequately sized dehumidifier, 1 pint capacity per 20sq.ft. of floor space. Most basement with dehumidifiers are not adequately sized. In real humided climates or very wet houses, check for the larger whole house dehumidifiers. EPA’s “Energy Star” web site for efficiency and capacity.