Things You'll Need
Mop (if needed)
If you live in an older house or just haven't cleaned your tiles in a while, you may notice that you have old dirty grout. Unlike newer or more frequently washed grout, this grout will require a pretty heavy-duty cleaning to make it look like it did when it was first put down. That doesn't mean it isn't possible. It just means you need to be patient and committed to the work you need to do.
Put six cups of warm water in your bucket and add five cups of oxygenated bleach. Stir in the bleach with a mixing spoon until it dissolves. You'll have a cloudy liquid.
Dip your sponge in the bucket and squeeze it tightly as you lift it out so that excess cleaning solution goes back into the bucket. Wipe the grout with the sponge until every piece of it is saturated. You may need to dip the sponge in the bucket several times.
Wait 15 minutes to allow the solution to sit on the tile and begin attacking the stains. (You may notice it bubbling up.) Pour clean water on the grout if the cleaning solution has dried. Then scrub it with your brush. Move the brush in circles, not back and forth, so you don't end up digging it into any soft areas of the grout. Use medium to heavy pressure.
Wet a cotton rag with lukewarm water and wipe down the grout to remove any dirt that has come up from your cleaning. Rinse the rag whenever it gets too dirty.
Dump the bucket and fill it with new water. Wet mop your grout and the tile surrounding it. Use a mop if it's on the floor. If not, use another rag.
Let the grout dry for half an hour. (It's hard to see if it's clean since it will look darker when it's wet.) Check to see how your grout looks after it dries and repeat Steps 2 and 3, if you need to.
After cleaning, seal your grout so it can’t get a dirt buildup on it in the future. Spot clean grout after your deep cleaning by using an old toothbrush and some baking soda. Add water to the baking soda to create a paste.
Always use oxygenated bleach as opposed to chlorine bleach. Chlorine bleach can cause spotting, especially on colored grout.