How to Clean Grout
What You'll Need
- 1/2 cup
- 1/4 cup
- 1 tsp
- 1
- 1
- 1
Step-by-Step Method
Combine 1/2 cup baking soda, 1/4 cup hydrogen peroxide (3%), and 1 tsp dish soap in a bowl. Mix until you get a thick paste.
Using your finger or the brush, apply the paste directly onto the grout lines. Work in 3-4 foot sections so the paste doesn't dry out before you scrub.
Allow the paste to sit on the grout for 10-15 minutes. The hydrogen peroxide and baking soda need time to break down stains and mildew.
Using a stiff grout brush (or old toothbrush for small areas), scrub the grout lines in a circular motion. Apply firm pressure but do not damage the grout.
Rinse the area thoroughly with clean water. Wipe dry with a clean towel. Inspect the grout. Repeat steps 2-5 on any remaining stained sections.
- Do not use bleach on colored grout (it will lighten the color)
- Do not use metal brushes or steel wool (they chip grout)
- Do not mix hydrogen peroxide with vinegar (creates peracetic acid, a skin and lung irritant)
- After cleaning, apply a grout sealer to protect against future staining. Most sealers last 1-2 years.
- For grout that is permanently discolored, grout paint pens can restore a uniform appearance without re-grouting
- Ventilate the room when using hydrogen peroxide, especially in small bathrooms
Frequently Asked Questions
Grout is porous and absorbs moisture, dirt, mildew, and soap residue over time. In bathrooms, mildew is the most common cause. In kitchens, grease and food splatter. Unsealed grout stains faster.
Only on white grout. Bleach can lighten or discolor colored grout permanently. Even on white grout, the hydrogen peroxide method is gentler and almost as effective. Save bleach for severe mold situations.
Sources & Methodology
Hydrogen peroxide (H2O2) is a mild oxidizer that breaks down organic stains and kills mildew on contact. Safe for most tile and grout at 3% concentration.
Last reviewed: March 20, 2026