For White Grout

• 1). Mix five parts water with one part bleach. For grout on walls, distribute the mixture into a spray bottle. For grout on floors, you can pour the mixture directly into the grout lines. Always wear protective gloves when handling bleach.
  
  
• 2). Pour or spray the bleach solution onto the grout and let it settle. The bleach will penetrate the porous grout and slowly break down dirt, stains and mildew. Wait approximately 15 minutes before proceeding.
  
  
• 3). Scrub your grout with a clean toothbrush to further loosen the dirt particles. Rinse away the bleach with water and allow the grout to dry. For really old, set-in stains, apply a second coating of diluted bleach and scrub the grout again.
  
  

For Colored Grout

• 1). Pour 1/4 cup of water over 3/4 cup of baking soda and mix until you have a firm paste. You should never use bleach on colored grout, as the color will permanently lighten, but baking soda can make an effective cleaning solution for kitchen and bathroom grout.
  
  
• 2). Apply the paste to your grout and immediately begin scrubbing vigorously with a toothbrush, loosening the dirt particles. Wait approximately 15 minutes and then proceed to the next step.
  
  
• 3). Rinse your colored grout with water to remove the baking soda paste, and then allow the surface to dry. Add a second application of baking soda if necessary.