Old tile grout may become stained or dirty over time. Whether the grout is in the bathroom or kitchen, on the floor or on the wall, keeping it clean will make the entire surface look neat. Dirty tile grout diminishes the appearance of the tiled surface. It is also important to clean old grout properly so the tile itself does not become damaged.
Sweep the grout joints thoroughly. Use a vacuum cleaner attachment brush or broom to remove loose dirt and debris from the joints.
Fill a bucket with warm water. Dip a rag into the water and wring it out lightly.
Scrub the tiles with the rag and warm water to loosen built-up dirt and grime from the grout lines. Rinse and wring out the rag frequently. Let the grout joints air dry completely before moving on to clean with a cleaning solution.
Combine three parts baking soda and one part water into a bowl and stir to form a paste. Use a kitchen spatula or plastic putty knife to spread the paste onto the dirty tile grout. Let the paste sit on the grout for about one hour.
Scrub the paste into the grout with an old toothbrush after at least one hour has elapsed. Use a circular motion when scrubbing to effectively lift the build-up and grime from the joints.
Rinse the baking soda paste from the grout lines with a rag and water. Rinse out the rag often to avoid reapplying the paste to the surface. Go over the grout lines with a dry rag to remove excess moisture.
Mix 118ml oxygen bleach with one gallon of warm water if the old grout is still dirty. Dip an old toothbrush into the oxygen bleach solution and scrub the tile grout in a circular motion.
Let the oxygen bleach sit on the grout for up to 30 minutes. Rinse the grout with a rag and plain water. Dry thoroughly with clean rags.
Apply grout sealer to the grout joints once a year after they have been thoroughly cleaned. Sealing the grout will help to keep it clean.