Baking Soda

• Baking soda has the ability to penetrate grout and remove difficult stains, all without presenting a strain on the environment. Create a thick baking soda paste by mixing 3/4 cup of baking soda and 1/4 cup of water. Use a toothbrush or thin scrub brush to work the paste into the grout and scrub the surface with complete accuracy and control. For best results, wait 15 minutes and then rinse.
  
  

White Vinegar

• White vinegar (sometimes called distilled vinegar) is another natural, eco-friendly cleaning agent useful on grout. The acetic acid contains anti-fungal properties, so vinegar is especially useful for mildewed grout. Since acetic acid also dissolves mineral deposits, you may also want to use it if your grout shows signs of hard water spots or rust. Spray vinegar directly over your grout and wait 15 minutes before scrubbing and rinsing. Do not use vinegar on grout that surrounds natural stone like marble or granite, but feel free to use it on porcelain, ceramic, quarry or synthetic tile grout.
  
  

Oxygen Bleach

• Oxygen bleach is the environmentally sound alternative to chlorine bleach. Oxygen bleach contains no harsh chemicals or toxic fumes and uses only natural oxygen ions to dissolve dirt, minerals, soap scum and mildew. Typically available in powdered forms, you must mix the bleach with water according to manufacturer's instructions before spraying or pouring it over grout. For a natural liquid alternative to oxygen bleach, use hydrogen peroxide diluted with equal parts water. Hydrogen peroxide is a similar natural bleaching agent.
  
  

Ammonia

• Ammonia, usually marketed in large plastic bottles as "clear ammonia," is natural and useful for cleaning grout. While you can achieve some results by mixing a cup of ammonia with a gallon of water, you will want to mix it with other natural ingredients to create a truly powerful cleaning solution. Try mixing 7 cups of water, 1/3 cup of ammonia, 1/2 cup of baking soda and 1/4 cup of white vinegar, as recommended by Mrs. Clean USA.