How to Clean Dark and Discolored Tile Grout

Dark grout can be cleaned using a paste made from baking soda and water, scrubbed with an old toothbrush, then rinsed thoroughly with clean water.

1. Gather Your Arsenal. Remove all items from the tiled surface and sweep or vacuum any loose debris. Gather baking soda, water, an old toothbrush or grout brush, clean rags, and rubber gloves. Open windows or turn on ventilation fans to improve air circulation.
2. Mix Your Secret Weapon. Mix three parts baking soda with one part water in a small bowl to create a thick paste. The consistency should be similar to toothpaste. This gentle abrasive will lift dirt and stains without damaging the grout.
3. Target the Darkest Lines. Using your finger or a small spoon, spread the baking soda paste generously along the darkened grout lines. Focus on the most discolored areas first. Let the paste sit for 10-15 minutes to penetrate the stains.
4. Scrub With Intent. Use an old toothbrush or dedicated grout brush to scrub the paste into the grout lines using circular motions. Apply firm pressure but avoid being too aggressive, as this can damage the grout. Work in small sections of about 3-4 square feet at a time.
5. Reveal Your Progress. Wipe away the paste with a damp cloth and rinse the area thoroughly with clean water. Check your progress and repeat the process on any remaining dark spots. For stubborn stains, let the paste sit longer before scrubbing.
6. Finish Bright and Dry. Once all grout lines are clean, wipe down the entire tiled surface with a clean, damp cloth to remove any residue. Dry the area completely with a clean towel or allow it to air dry. The grout should return to its original lighter color.