Hot water extraction

It involves a combination of hot water and cleaning agents being injected into the fibers of a carpet at high pressure and the lifted soil being removed by a powerful vacuum.

HWE begins with preconditioning using a pre-spray cleaner (typically neutral or alkaline) being applied to the soiled surface, followed by light agitation with a grooming or pile brush.

Next, the surface is passed over several times with a cleaning wand or rotary extractor to thoroughly rinse out the preconditioner, using an acidic solution to reduce the pH of the carpet fibers back to a neutral state.

Consumer-grade and rental machines use similar technology to professional systems, but with less power and usually without an element to heat water.

These units are not typically labeled as HWE systems, but are called "extration vacuum cleaners", and may have additional heads for cleaning non-fabric surfaces like hard floors.

Example of the steam cleaning method, using a carpet cleaning wand.
Truck-mounted hot water extraction machine
Consumer-grade extraction cleaner by Bissell . 3-liter fluid capacity; no heating element. A button on the vacuum-head dispenses the cleaning fluid (special soapwater) by air pressure.