Carpets take a beating every day: kids, pets, everyday foot traffic, not to mention the mud and debris from outdoors. To clean your carpets without chemicals, simply mix equal parts of vinegar and water in a spray bottle. Spray the mixture on your carpet stains, then let it sit for a few minutes. Scrub it off with dish detergent. This is effective for most stains.
Deep set stains or grease may need a different approach. For deep set stains, make a paste of 1/4 cup borax, 1/4 cup salt, and 1/2 cup vinegar. Apply the paste to the stains and allow it to sit for several hours. Then simply vacuum it away. If grease or tar are a problem, sprinkle the area with cornstarch and then vacuum it away.