Having carpets periodically cleaned makes them last longer and look better, and it improves your home’s air quality.

The company you hire will impact how well the job gets done, whether difficult stains are removed, how good your carpets and rugs look afterward, and how long they stay that way. With the least-competent companies you risk permanent damage from overwetting, improper or poorly mixed chemicals, bad brushing, and other shoddy practices.

Collect Feedback from Customers

We surveyed consumers in seven major metro areas and asked them to rate carpet cleaning services they had used recently on questions such as “neatness,” “doing work properly on the first try,” “promptness,” “advice on service options and costs,” and “overall quality.” We found that many professional cleaning services consistently perform great work. The highest-rated companies were rated “superior” by more than 90 percent of their surveyed customers on most of our questions. But some other companies received low scores.

Complaint Records

Also check companies’ complaint histories with local consumer agencies, such as a local government consumer agency or the Better Business Bureau (BBB).

Guarantees

Most carpet-cleaning outfits provide guarantees, but their promises vary. Give companies credit if they talk candidly about their limitations before they begin the work—some stains are extremely difficult or even impossible to remove once they’ve set, and companies may not know whether they can zap them until they try.

Some companies may have you sign forms in advance explicitly excluding a wide range of trouble spots from their responsibility. Look for another outfit that does promise to take care of the problems that concern you.

If your carpet is still under its manufacturer’s warranty, also ask the company if its services keep the warranty in effect. Carpet manufacturers’ warranties are notably murky about coverage for “wear” and “appearance,” and many include a clause declaring that, for certain sections of the warranty to remain in effect, the buyer must prove the carpet was “professionally maintained.” This typically means the carpet must be professionally cleaned once every 12 to 18 months via a hot-water-extraction method. That’s a very expensive requirement, but if you care about warranty coverage, show the policy to the cleaning service and have it assure you that its services meet the requirements.

Do They Use Effective Cleaning Methods?

Some cleaning methods work better than others, depending on the condition of your carpet or rugs. Most Oriental rugs should be cleaned at a company’s plant using an immersion method—Click here for details and best practices for rug-cleaning jobs. For lightly soiled carpet, any method performed properly is acceptable, but in most cases you’re best off with a company that offers hot-water extraction with truck-mounted equipment.

Here’s a rundown of the pros and cons of various methods:

Hot Water Extraction

Also called “steam cleaning,” this technique sprays hot water (or water plus a mild detergent) into carpet pile and then immediately vacuums it—and grime—out. Performed properly, hot water extraction can clean even filthy carpets.

Hot water extraction is done with portable units or truck-mounted equipment; the latter generally works better on really dirty carpets—its higher temperatures and pressure penetrate deeply into carpet pile.

The extraction machines work better if the carpet is sprayed with conditioner and lightly agitated with brushes before cleaning. The conditioner acts as a degreasing agent, which assists in removing dirt and grime; it also lubricates the carpet so the hot-water-extraction wand doesn’t distort the pile.

For years, companies affiliated with the Chem-Dry brand used a modified bonnet method (see next page), but most now usually use its hot-water-extraction method, which mixes in a carbonated solution that, in theory, requires less moisture to be effective.

Shampoo

Carpet shampoos are a lot like laundry detergent. Some also contain chemicals to reduce odor, retard soiling, brighten colors, and speed drying. Cleaners use a rotary brush that releases shampoo onto the carpet, converts it into foam, and works it in. When the shampoo dries, it leaves dry particles that can be vacuumed up.

However, those loosened dirt particles might not get removed and may simply work deeper into the pile. Too much (or lousy) detergent may cause a sticky buildup on carpet fibers. And repeated cleanings without proper extraction can compound this problem, accelerating re-soiling.

Combined Shampoo and Hot Water Extraction

High-powered truck-mounted hot-water-extraction equipment usually cleans even heavily soiled carpet—especially if it is treated with conditioner. But for really grimy jobs, some companies recommend a two-step shampoo-then-hot-water-extraction process.

Foams

Foams are really just a form of shampoo. The foam is generated by machines that also agitate it on the carpet with brushes. You can use aerosol cans of foam at home, applying it in a thin layer and rubbing it in with a damp sponge. When it dries, simply vacuum up the residue. The main advantage to do-it-yourself users is that foam contains very little moisture, so you’re unlikely to damage carpet by getting it too wet. But this also means that not much soil is removed, so you’re cleaning only the carpet’s surface. Plus, some foams are difficult to rinse out and may interfere with later cleaning attempts.

Bonnet

Originally meant for commercial carpeting, bonnet cleaning uses a round absorbent pad, or bonnet, attached to the bottom of a rotary floor machine. Detergent is sprayed onto the carpet; then the pad is rotated over the surface, removing soil that adheres to it. When one side of the pad is soiled, it is reversed; when both sides are soiled, the pad is rinsed.

The bonnet method shares many of the same limitations as shampooing—many loosened dirt particles are never removed and simply work their way deeper into the carpet pile. The incorrect amount of detergent may produce a sticky buildup. And since companies using this method rarely employ a rinse process, repeated cleanings can overload the carpet with residues that may accelerate re-soiling.

Absorbent Dry Compounds

Dry powdery compounds containing detergents or solvents can be sprinkled on the carpet, worked into the pile by machine, then removed by a vacuum cleaner. The detergent or solvent dissolves the oily film on carpet fibers, freeing the soil to be vacuumed out along with the powder after about half an hour. Although usually less effective than other methods, dry compound cleaning has special applications.