This is the only cleaning method classified as “deep cleaning”. Most other methods are regarded “light surface cleaning” because they are incapable of removing soil deep in the carpet. Also, all other methods leave large amounts of cleaning agent in the carpet after cleaning, whereas steam cleaning is based around hot water.
This method is frequently called “steam” cleaning due to the fine pressurised spray of water used to force dirt out of your carpet which is then sucked up by the vacuum slot immediately in front of the spray. This process consists of spraying a solution of water and detergent into the carpet and recovering the water and soil with a powerful vacuum into a holding tank. This is commonly done from a truck-mounted unit outside the home with only the hose and floor tool brought inside, sometimes a portable system brought into the home or office if your home is difficult to access.
From a health point of view, truck-mounted systems are preferred because the dirty air and humidity are directly extracted outside rather than recirculated around the house. Additionally, truck-mounted systems usually are more powerful than portable units and do a much better cleaning job and get the carpet dry more quickly because the vacuum unit can be much larger than a portable ones.
With some truck-mounted systems, the vehicle itself must run in neutral during the cleaning and in many others a separate engine is used to power the unit and heat the water. In both cases, the van MUST be parked well away from the house and positioned so that exhaust fumes do not enter the house.
The most common form of steam cleaning (or hot water extraction) is a one-stage process. This is where a cleaner will bring a portable machine to your home, similar to the machine you can hire from your local supermarket. This machine is filled with water and detergent.
This method doesn’t clean your carpet as well as professional methods, and usually leaves a detergen residue behind in your carpet which will then promote rapid resoiling. This method is quite old and is not the preferred method by most carpet cleaners, having said that, it is still being used by a lot of bait and switch operators!