Although there is an industrial cleaning process that is in fact steam cleaning, in the context of carpet cleaning, “steam cleaning” is usually a misnomer for or mis-characterization of the hot water extraction cleaning method. The hot water extraction cleaning method uses equipment that sprays heated water (not steam), sometimes with added cleaning chemicals, on the carpet while simultaneously vacuuming the sprayed water along with any dislodged and dissolved dirt. Many carpet manufacturers recommend professional hot water extraction as the most effective carpet cleaning method. Actual steam could damage man-made carpet fibers or shrink natural fibers such as wool. A variety of hot water extraction carpet cleaning equipment is available, with less expensive equipment marketed for purchase or rental by homeowners, and more expensive equipment used by professional carpet cleaners. The more expensive commercial equipment may employ a rotating high pressure spray and extraction disc. This allows the equipment to achieve many spray-extraction cycles independent of the forward or backward motion of the machine.