When the carpets in a building become dirty, different methods can be used to clean them. Low moisture, also called dry cleaning, and hot water extraction, referred to as steam cleaning, are the two major carpet cleaning techniques. The process, benefits, and drawbacks vary between the two and building managers should understand the differences before they hire a professional to clean carpets in the facility.

All carpet cleaning methods use water so the process of “dry cleaning” carpets is not water-free. This low moisture cleaning system uses transference or absorption to remove soil. Though the process is quick, inexpensive, and shortens carpet drying time, carpet is not rinsed so soil and detergent residue typically remain.

There are three types of low moisture cleaning methods: dry foam, absorbent pad, and dry, absorbent powder. Dry foam is a crystallizing shampoo that dries and is removed from carpet with a vacuum. It is not considered a stand-alone cleaning process but is typically used before hot water extraction cleaning. The absorbent pad method involves placing a large cotton bonnet on carpet and rotating it to absorb dirt from carpet fibers without flushing. The powder technique uses a moist, absorbent powder that dries and is sucked into a vacuum.

Hot water extraction applies a hot water cleaning solution to the carpet and uses a vacuum to quickly remove it. All carpet manufacturers recommend this cleaning method, with some saying it offers the best cleaning capability. A hot water extraction system uses the most powerful cleaning equipment on the market. It removes dirt and contaminants like fungi, bacteria, chemicals, tobacco residue, and pollens from carpets. Contrary to popular belief, hot water does not damage carpet while removing dirt and soap residue.

The equipment in a hot water extraction system used by cleaning services is either truck-mounted or portable. The truck-mounted version features more heat, higher water pressure, and a vacuum that can recover up to 95 percent of water used during cleaning. A portable system can clean areas unreachable by a truck-mounted system, such as offices on higher floors of a commercial building.

Heating water accelerates the chemical reactions in cleaning solutions and reduces water surface tension for faster cleaning. Heat increases soil emulsification and leads to faster breakdown of soil. Wet extraction removes a wider range of soils but results in longer carpet drying times so it is recommended only for deep restoration cleaning. Dry extraction is used for daily or interim carpet maintenance.