If you can smell mildew on your carpet, chances are that mold is just about to grow, or is already beginning to grow, in it or on the pad below. Not only does mildew smell unpleasant, but it can also be unhealthy as mold produces allergens that can irritate your eyes, skin and throat. Rather than just cover up the musty smell, get to the root of the problem, such as a water leak, and then work on freshening up your carpet.
If your carpet, pad underneath or large area rug is damp or wet for any reason, such as from cleaning, high humidity or water spills, mold may begin to grow and produce the familiar musty mildew smell. For mold spores to grow and thrive, they need moisture, oxygen and a food source, so eliminate these things immediately. Basement carpets are at a particularly high risk of mold growth due to a lack of air flow and a damp environment. If excessive mold is already growing on the carpet or padding, you most likely will need to replace it. If it hasn't started yet, you can rent or buy a heavy-duty carpet cleaner and thoroughly clean the flooring using a commercial carpet shampoo. Allow the carpet to completely dry by opening windows, using fans or a combination of both, before walking on it.
After thoroughly cleaning and drying your smelly carpet, you can eliminate any lingering musty smell with distilled white vinegar. Begin by mixing 1 cup of vinegar with 2 cups of warm water in a spray bottle. Spray the solution all over the portions of the carpet that have an odor, covering but not oversaturating the fibers. Next, sprinkle baking soda, which will help lift the smell out of the carpet, all over the affected area. Open windows or turn on a fan or two to help speed up the drying process. When the carpet is dry, vacuum up the baking soda.
Another way to get rid of a musty carpet smell is with borax, a natural alkaline mineral salt that will deodorize the fibers and help keep any mold growth from reoccurring. Sprinkle a generous amount of borax over the carpet and allow it to sit for 30 minutes before vacuuming it up.
Once you've eradicated the mildew smell in your carpet, prevent it from occurring again with a few simple precautions. For instance, if you live in a climate with high humidity, or if your basement is carpeted, run a dehumidifier all year round, as well as an air conditioner during the summer months, to reduce moisture. The air conditioner will also increase air circulation throughout the space, as will open windows. Be sure to change the dehumidifier and air conditioner filters as recommended by the manufacturers. If you spill any liquids on your carpet or rug, clean the stain up right away and allow it to thoroughly dry.