Eliminate musty smells from a home by searching for the areas where mold and mildew grow and removing the fungus. If you do not find a single source, you must take a broad approach that involves deep cleaning of all surfaces with a mildew killing agent such as bleach.
Begin the search for mold or mildew growth in areas of the home where moisture is likely present, such as the kitchen, laundry, bathroom and basement. Remove any materials that could hide mildew, such as shower curtains, laundry piles, newspaper piles and old boxes. If you find a concentrated source of the musty odor, clean it to restore a fresh smell to the home.
If you do not find growing mold, mix one part bleach to four parts of water, and clean all the hard surfaces in the room. Rinse with plain water after cleaning with bleach. Use bleach in the washing machine to wash and dry all fabric items such as curtains and clothing. Be sure to wash any sneakers from the rooms that may harbor mold.
Prevent the return of the odor by operating a dehumidifier in the area. Use a vent fan in the kitchen and bath to reduce moisture. Fill large containers with baking soda, charcoal or kitty litter, and place them around the space to absorb any remaining odors.