I have been using Mean Green to shampoo my carpets for years. I use about 1/2 cup per gallon of water and it doesn't clog up your pump like pine oil will.
Cleaning Carpet
Make Your Own Cleaning Products
Homemade Carpet Cleaner Recipes
Using Vinegar and Water in a Carpet Cleaner
Using Shampoo as a Carpet Stain Remover
Removing Mildew from Carpet
Cleaning Dog Urine Stains from Carpet
Homemade Furniture Polish Recipes