How to Clean Grout Lines in Shower Tile

Grout lines collect everything—soap scum, mildew, hard water deposits, and the general dampness that comes with daily showers. Left alone, they darken and trap bacteria. The good news is that grout cleaning is straightforward work that requires no special skills, just the right approach and patience. When done properly, your tile looks new again, the shower feels genuinely cleaner, and you've prevented the kind of stubborn staining that gets exponentially harder to fix. A few hours of attention now saves you from chasing impossible discoloration later.

1. Clear and dry the shower first. Remove all bottles, caddies, and loose items from the shower. Use a towel or squeegee to wipe down the tile surfaces and grout lines until they're completely dry. Grout cleaners work best on dry surfaces—wet grout traps moisture and prevents thorough cleaning.
2. Mix the perfect paste. In a small bowl, combine three parts baking soda with one part water. Stir until you reach a thick paste that clings to a brush without running. If it's too thin, add more baking soda; if it won't spread, add water a teaspoon at a time. This is your workhorse for regular maintenance cleaning.
3. Work paste into every line. Using an old toothbrush or a dedicated grout brush, work the paste directly into the grout lines. Start at the top of the shower and work downward so you don't have to reach over wet areas. Press firmly into each line, coating the entire length. You're aiming for a thick, visible layer.
4. Scrub hard perpendicular to lines. Using your brush, scrub the grout lines with short, firm strokes perpendicular to the line—not lengthwise. This motion dislodges trapped debris and breaks up surface buildup. Spend extra time on lines that show visible discoloration or mold. You should see the paste darken as it picks up grime.
5. Rinse every trace of paste away. Use the shower head to rinse away all the baking soda paste. Start at the top and rinse downward, making sure no paste residue remains in the lines. Go over each area at least twice—baking soda residue will whiten grout if left behind. The grout should look noticeably lighter and cleaner.
6. Attack stubborn stains chemically. For mold or stains that baking soda didn't fully remove, spray 3% hydrogen peroxide directly onto the grout lines and let it sit for 10 minutes. The peroxide will bubble slightly as it breaks down organic stains. Scrub again with your brush, then rinse thoroughly. Hydrogen peroxide is gentler than bleach but still effective on most bathroom mold.
7. Go nuclear as last resort only. If hydrogen peroxide doesn't work, mix one part household bleach with ten parts water in a spray bottle. Spray the affected grout lines and let sit for 15 minutes—no longer, as bleach can damage grout if left too long. Scrub firmly, then rinse multiple times until no bleach smell remains. Ventilate the bathroom thoroughly during and after this step.
8. Eliminate every trace of moisture. Use a towel or squeegee to remove standing water from all surfaces. Wipe the grout lines specifically to prevent water from sitting in them. Leave the bathroom ventilation fan running for at least 30 minutes after cleaning to evaporate remaining moisture.
9. Check for structural damage. Once dry, examine the grout closely. If it looks soft, crumbly, or has gaps where pieces are missing, the grout may need replacement rather than cleaning. Surface discoloration is normal and cleanable; structural damage is not. Mark any problem areas for future regrouting.
10. Seal grout to protect progress. If your grout is in good condition and you want to reduce future staining and mold growth, apply a penetrating grout sealer according to product directions. Most sealers require the grout to be completely dry (wait 24-48 hours after cleaning). Apply with a small brush, bottle applicator, or caulk gun depending on the product. Wipe excess sealer off tile immediately.
11. Commit to weekly five-minute cleanings. Clean grout lines weekly with baking soda paste to prevent heavy buildup. After each shower, squeegee or towel-dry the tile to minimize standing water. This routine prevents mold and keeps stains from setting in, so monthly deep cleans become unnecessary.