How to Deep Clean and Protect Shower Grout

Grout acts like a sponge, soaking up soap scum, body oils, and minerals that eventually turn into a breeding ground for mildew. When you see dark, fuzzy spots appearing between your tiles, you are looking at porous material that has lost its defense against the humid environment of your bathroom. Restoring your shower requires more than just a quick scrub; it needs a chemical break down of the organic matter and a physical barrier to keep it from coming back. Done well, your grout returns to its original color and remains resistant to water for a year or more. Forget harsh bleaches that eat away at the mortar; focus on pH-neutral cleaning and a quality sealer.

1. Paste Out the Mildew. Mix baking soda and hydrogen peroxide into a thick paste. Apply this directly to the grout lines and let it sit for 15 minutes to break down soap scum and kill mildew spores.
2. Agitate Deep Into Grout. Use a stiff-bristled grout brush to scrub in a circular motion. Apply moderate pressure to lift the grime out of the recessed areas between the tiles.
3. Clear Every Trace. Rinse the tiles with warm water to remove all traces of the baking soda paste. Wipe down the entire wall with a clean microfiber cloth to ensure no residue remains.
4. Wait Before You Seal. Run a squeegee over the tiles and allow the shower to air dry for at least 24 hours. Sealer will not adhere to damp or humid grout.
5. Lock in Protection Now. Use a foam applicator or a bottle with a needle-nose tip to apply a thin bead of grout sealer over every line. Wipe away any excess sealer from the surface of the tiles before it dries.
6. Give the Seal Time. Allow the sealer to cure for at least 24 hours before allowing water to touch the shower walls. Avoid using harsh chemical cleaners for the next week while the bond settles.