Cost: about 50 cents per square foot for hot water extraction cleaning, or $500 for 1,000 square feet of cleaned carpet.
How often: every 12 months; more often for high-traffic areas and homes with small children, pets or smokers. Manufacturers' warranties may require cleaning every 18 to 24 months. You can save money by focusing on regular cleanings for high-traffic areas and waiting up to two years for the entire carpet.
When: any time.
If the carpet looks dirty, you've waited too long because some soil can't be removed with vacuuming. This soil will bind to your carpet and dull the texture, shortening the life of the carpet.
Your home also will be healthier with pollen, bacteria, insecticides and dirt removed, says Howard Partridge, founder and president of Clean as a Whistle, a cleaning company outside Houston.
Potential savings: extending the life of your carpet. Replacing 1,000 square feet of medium-grade carpet, including padding and installation, costs about $3,000.
Bottom line: "One of my neighbors had to replace his carpet in less than four years," Partridge says. "And his carpet looked terrible the whole time. I've been able to keep my carpet for 12 years now."