Too much moisture can easily turn carpets into a breeding ground for bacteria. The best way to combat mold is to prevent its growth in the first place. To do this, it's important to eliminate any conditions that could lead to its growth. Controlling indoor humidity is the key to preventing mold growth on carpets.
Vacuuming the surface thoroughly and quickly removing as much water as possible is essential. If you're not sure you're doing a good job yourself, you can also hire professional water disposal services. Organic carpets, such as wool, are more prone to mold growth than inorganic or synthetic carpets, such as nylon or olefin. If your carpet has been damaged by water, it may be more cost-effective to replace the entire carpet than just the padding or backing.
A study conducted by the Carpet and Rug Institute (CRI) found that when a clean nylon carpet was exposed to high temperatures and humidity levels (80 degrees F; 80 percent humidity), no mold growth occurred. Other studies have been conducted to determine if high humidity (such as that found in a basement or facility below ground level) causes mold to grow on carpets. If the heating, ventilation, and air conditioning system shuts down during or shortly after cleaning tasks that involve a lot of water, such as mopping or shampooing carpets, humidity levels may increase significantly and cause moisture or mold problems. It's generally accepted that moisture is the main cause of mold in carpets and that if moisture is removed from the carpet, the mold problem will be solved.
Even if you can't see any visible signs of mold on the surface of the carpet, it doesn't mean that it isn't growing. Rugs in various conditions (new, old, dirty and clean) were exposed to different levels of humidity in a study. Clean carpets were found to be very resistant to mold growth even in damp conditions. The deep pile of carpets can house dormant mold spores accumulated over time, along with microscopic organic material that nourishes skin cells, small pieces of food, hair, insect parts, and even common dust.
Dirty carpets were found to generate much more mold than clean carpets when exposed to the same levels of humidity. It's worth noting that if a carpet is clean enough, it's very resistant to mold growth despite damp conditions. Even clean carpets that were known to have active mold spores didn't allow more mold to grow when exposed to high levels of humidity. The light moisture found in basements builds up over time and can cause problems with carpets and other materials.
In most cases, if the carpet padding has been in direct contact with water, it will need to be changed. If you have a carpet in an area with potentially high humidity, you should always remove moisture from the area and keep temperatures low.