A Carpet & Upholstery Cleaning can address moderate and heavy soil conditions in your carpets. How often you'll need professional cleaning depends on soil build-up, traffic, type and color of carpeting. A good rule of thumb would be to professionally clean your carpet every 12 months. The best advice is to clean carpets before they become totally saturated with soil. If you wait until carpets look really dirty, the carpets may never be restored to their former appearance. Dirt builds up in layers, and when a carpet looks dirty you are only seeing the dirt at the tips of the fibers. More dirt is hiding below the surface down near the base of the pile, causing damage to the carpet. When a carpet is saturated with dirt, the soil has penetrated crevices and has become firmly lodged.