How to Remove Mold from Shower Grout

Grout is a magnet for mold because it acts like a sponge, soaking up moisture, skin cells, and soap scum. Once the dark, fuzzy spots appear in your shower, they aren't just an eyesore; they are a sign that the sealant has failed and the porous cement is trapping bacteria deep within its structure. Restoring your shower to a sanitary state requires more than a casual wipe-down. To do this well, you need to break down the biofilm that holds the mold in place and then chemically kill the spores before they spread further into the wall cavity. Follow this process to reclaim your tile lines and prevent future growth.

1. Eliminate all surface moisture. Wipe the shower walls down with a clean, dry microfiber cloth to remove excess moisture. Mold cannot be effectively treated when the grout is already saturated with water.
2. Coat every affected grout line. Mix a paste of baking soda and hydrogen peroxide, or apply a dedicated grout bleach cleaner directly to the grout lines. Ensure every spot of mold is covered with a thick, visible layer of the treatment.
3. Let chemistry do the work. Allow the cleaner to sit undisturbed for at least 30 minutes. This dwell time allows the active agents to penetrate the porous grout and break the molecular bond of the mold spores.
4. Attack with circular pressure. Use a stiff-bristled grout brush to scrub in a circular motion along every grout line. Focus your effort on the heavily stained corners and the bottom three rows of tile.
5. Flush away all residue. Use a handheld shower head or a bucket of clean water to rinse the walls from top to bottom. Ensure all residue is washed into the drain to prevent it from drying into a film.
6. Lock in permanent protection. Once the grout is 100% dry, apply a high-quality penetrating grout sealer. This creates a hydrophobic barrier that prevents water and soap scum from sinking into the grout in the future.