Mold accumulates in the bathroom when moisture and steam from the shower settle onto bathroom surfaces. Over time, this moisture turns into mildew and mould development. When your tile and grout have collected mould, you need a cleaning solution that gets rid of the mould and bacteria without damaging the grout or tile. A few inexpensive household items will both clean the grout and remove the mouldy residue and kill any bacteria.
Rinse a nylon scrub brush under hot water. Sprinkle a heavy coat of baking soda onto the brush and scrub it into the mouldy grout. This is a mild abrasive cleaner that is safe for tile and grout, plus breaks apart mould and dirt build-up.
Rinse the grout with hot water.
Soak paper towels in white vinegar, then lay them on top of the grout. The paper towels will stick to shower walls as well without falling off. Let the paper towels sit for 1 hour.
Remove the paper towels, scrub the grout with the nylon brush and rinse the grout again.
Mix 1 qt. hot water and 2 cups oxygen bleach in a bucket. Soak paper towels in this mixture and lay them over the grout. Let sit for 1 hour.
Remove the paper towels, dip the scrub brush in the remaining cleaning solution and scrub over the grout until all remaining mould is gone. Rinse the grout when all mould is gone.