My Basement Smells Like Mildew
If your basement smells like mildew, then you have mold growing in your basement. Because this can be a health hazard, it should be cleaned as soon as possible. Removing mold and mildew will also remove the musty mildew odor from your basement.
Create a solution of 1 ounce bleach to one quart water, and pour it into a squirt bottle. Spray the solution on affected floors and ceilings that are bleach safe, such as cinder blocks and cement. Scrub the mildew away, then rinse with water, as recommended by the book "2,001 Amazing Cleaning Secrets," by Jeff Bredenberg.
To clear the smell of mildew from your basement, you can sprinkle chlorinated lime powder onto the floor. The powder will absorb the smell. Once the air in the basement smells better, sweep up the powder and dispose of it.
To prevent mildew from returning to your basement and bringing its unpleasant odor with it, you can place a dehumidifier in the basement to keep moisture levels down. Increasing air circulation can also help. You can put activated alumina, anhydrous calcium sulfate, or other chemical drying agents in the basement to absorb excess moisture, according to the University of Georgia.