[header] How to repair grout [title] Clean the damaged grout with white vinegar and water. [step] That way you can see the exact color of the grout and buy new grout that matches it. Mix one part white vinegar and one part water in a bowl or bucket. 
Then, dip a clean toothbrush in the mixture and scrub the damaged grout until all the dirt and grime comes off. Wipe away the excess mixture with a cloth.