In a recent Technical Bulletin, Shaw Industries of Dalton, GA, the world's largest carpet manufacturer, recommends the hot water extraction system, which research indicates provides the best capability for cleaning.

You can choose from two different types:
Truck- mounted extraction, which is done with a large machine mounted in a truck or van, or
portable extraction, which is done with a small, hand-held unit.

On which type to choose, Shaw's Technical Bulletin states: "[cleaning] can be done from a truck-mounted unit outside the facility with only the hose and wand brought inside, or where a truck-mounted unit cannot reach, by a portable, self-contained system brought into the facility".

A truck-mounted unit cleans much better than a portable unit for these reasons:

• It heats the water to a higher temperature. For every 18 degree increase in temperature above 118 degrees F, you double the cleaning ability of the water. So if the water temperature is 136 degrees F, it will clean twice as well as water that is 118 degrees F.
  
  
• It shoots the cleaning solution into your carpet at higher pressures, which breaks up the dirt, bacteria, chemicals and pollens. The optimum pressure for truck-mounted hot water extraction is 200 to 300 pounds per square inch.
  
  
• The machine uses strong suction to draw the dirt, chemicals, bacteria, pollens and tobacco smoke residue out of your carpet.
  

The process is efficient because it is running from the horsepower of the engine of the truck rather than from standard household electricity.

Some people believe that hot water damages your carpet, but this isn't true. By washing and then rinsing your carpet with hot water, your carpet is completely clean in the same way that the person who showers and then rinses off the dirt and soap will be much cleaner than the person who takes only a sponge bath.