Carpets exposed to water or a damp environment can experience the growth of mould or mildew. Not just unattractive, mould and mildew cause respiratory or allergy difficulties for many people. If you see fuzzy or furry spots on your carpet, you likely have a mould problem. Mildew can be a little harder to spot, but often manifests itself in a thin white or bluish layer and a musty odour. If you have a carpet that's been affected by mould or mildew, it's a smart idea to tackle the job of killing the mould and mildew growth as quickly as possible.
Dry the carpet thoroughly. Place fans to blow on the carpet, put a dehumidifier in the room with the carpet, and ventilate the room as well as possible. If you can remove the carpet from the room and let in dry in the sunlight, that's an excellent course of action as well.
Wait until the carpet has dried thoroughly, then vacuum the mould and mildew affected areas with a shop vacuum. Wear a filter mask when doing this to prevent respiratory irritation. Remove as much of the dry mould and mildew as possible.
Mist the affected areas of the carpet with an antibacterial spray. Let the spray dry and vacuum again with a shop vacuum. If you don't want to employ chemicals in your home, use a mixture of 1 part denatured alcohol to 1 cup water, applied with a clean rag.
Repeat Step 3 several times if necessary to kill the mildew and mould.