The carpet “steam” cleaners that you can rent or have someone come in and use employ large amounts of hot water to clean your carpets. In reality, they are not even true steam cleaners but hot water extractors. These two machines run on very different principles. With hot water extraction, the carpet is saturated then the unit extracts dirt and debris trapped in the carpet fibers. While hot water extraction is a preferred method by most carpet manufacturers, the machine has negative consequences for those with allergies. The hot water used to clean leaves the carpets soggy for hours after cleaning them; wet carpets nurture the right conditions for mold and mildew to grow and multiply. Another difference in carpet steam cleaners is that most of them also use chemicals and cleaning agents mixed in with the hot water, so it is not an efficient way to clean for those who suffer from allergies or who are looking for a “green” product. Vapor steam cleaners clean only with water, no chemicals or cleaning agents are ever mixed in.