Mold and mildew are attracted to poorly lit, damp, warm places. Basements are a prime place for mould and mildew growth because basements are often dark and poorly aired. If mildew is permitted to grow, it can leave musty odours in basement carpeting. In extreme cases, mildew can even discolour or rot basement carpet. First treat the mildew before trying to remove the odours, as the odours will return. Fortunately, you can remove the foul odours caused by mildew from basement carpets by using the proper materials and techniques.
Remove the mildew from the basement by letting in sunlight through the windows. Raise the shades, draw back the drapes and let the sun beat down onto the carpet.
Open all of the windows in the basement to let in fresh air, which will help ventilate the room and remove any mildew smells from the carpet.
Put a dehumidifier in the basement to circulate the air in the room. It is pointless to only remove the odour without getting rid of the mildew itself first.
Sprinkle chlorinated lime all over the basement carpet, and leave it on the carpet until the mildew smell is gone. After the odour subsides, sweep the chlorinated lime up with a vacuum.
Lift up a corner of the carpet to see if the carpet padding is wet if the mildew smell persists. If the carpet padding is wet, vacuum the basement carpet with a wet vacuum, using a hot water extraction unit for water removal. Water under the carpet can cause mildew odours.
Rent a wet vacuum from a hardware store. Sprinkle baking soda on the carpet, and then vacuum it up. If the carpet padding is still wet after vacuuming, you may need to replace the padding.