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 mischaracterisation 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.
The primary advantage of the hot water extraction cleaning method is that effective cleaning is possible using only hot water, or hot water with very dilute detergent solutions. This avoids the problems associated with detergent residues that can remain in the carpet with other cleaning methods. Detergent residues on carpet fibers can attract dirt from the soles of shoes as people walk on a carpet, causing the carpet to become dirty again soon after cleaning.
Since the use of detergents and other chemicals is minimized or avoided altogether with the hot water extraction cleaning method, this method is advantageous for persons concerned about possible chemical exposure, especially for children crawling or playing on recently cleaned carpets. This method also minimizes concerns about breathing volatile chemical compounds that might be used in other cleaning methods.