Mix powdered oxygen bleach in a bucket with warm water. Use the manufacturer's recommended amount. Stir to dissolve.
Pour the solution directly onto dry grout. Dry grout is probably going to soak it right up. Keep applying the bleach water so there is always water sitting on the grout. If you're dealing with walls, pour the solution into a spray bottle and spray generously directly onto the grout. It might soak right in---if this is the case, just add more so the grout is wet. Let the solution sit for 30 minutes.
Scrub lightly after with a nylon-bristled brush, applying fresh solution as you scrub. If you scrub a small area and it's still not clean, apply more bleach water, let the solution sit for 10 more minutes and scrub again.
Rinse the grout with clean water.
Things You Will Need
- Powdered oxygen bleach
- Warm water
- Nylon-bristled scrub brush
- Clean rinse water
- Maintain clean grout by adding oxygen bleach to your mop water every time you clean the floors. Let the solution sit for 30 minutes, then rinse it clean.