2. Vinegar
If baking soda hasn’t restored the grout’s original color, you can use white vinegar. Pour vinegar into the grout and scrub it with a brush and baking soda.
3. Hydrogen Peroxide
If the grout’s blackening is due to mold, mix water and 3% hydrogen peroxide. Spray the mixture onto the grout and let it sit for 45 minutes before rinsing.
4. Epsom Salt
Epsom salt is useful for fighting bacteria and restoring whiteness to grout. Clean the grout with a damp cloth and coarse salt and leave it overnight before rinsing the next day.
5. Borax
Borax, available in supermarkets, is a natural disinfectant and deodorizer. Make a paste with borax and water and use it to clean the grout with a sponge or brush.