For the best results, use a new toothbrush with hard bristles, and scrub the grout in a circular motion, rather than back and forth. [2] X Research source When you have finished scrubbing the grout, use a spray bottle to spray the area with a half-and-half mixture of vinegar and water. [3] X Research source Let it bubble for about half an hour. Use the toothbrush to scrub the baking soda paste and vinegar into the grout again. Rinse the area with clean water.

You should never mix vinegar and hydrogen peroxide,[6] X Research source so clean the area well and wait a couple days before trying this method. If the hydrogen peroxide doesn’t remove all the dirt and grime, it will at least improve the appearance of the grout by removing stains, and will kill any mold that’s present. [7] X Research source

Use your toothbrush to scrub the paste into the grout, and then rinse with warm water.

Even if the steam cleaner doesn’t get the grout perfectly clean, it will clean it somewhat, and help loosen the rest of the dirt and debris to make it easier to clean with other products. [10] X Research source

Be sure to use these products in a well-ventilated area, and avoid contact with your skin. Always wear gloves to use these products. Always spot test commercial products in a small area on your grout to make sure the product won’t discolor, erode, or damage your grout. [13] X Research source Don’t use any sort of bleach product on colored grout.

Zep Goo Gone Grout Outrageous Tilex Tile and Grout

Pour a small amount of grout colorant into a container. Dip a clean toothbrush or grout brush into the color and apply it to the grout using even, back and forth strokes. [17] X Research source Remove the excess with a paper towel, and allow to dry as per the manufacturer’s instructions.

Half-and-half vinegar and water. [19] X Research source However, be aware that overuse of vinegar on grout can cause erosion over many years. Water and 15 to 20 drops of tea tree oil. Shake well before each use. Pure hydrogen peroxide in a spray bottle. [20] X Research source

If your bathroom isn’t equipped with an exhaust fan, remove moisture from the air after every shower or bath by opening the window and blowing a stand-up fan out the window.

One applied and cleaned, allow the sealant to cure for about three to four hours.