Sweep or vacuum the tiled area
Mix warm water with mild dish soap
Apply the solution to the grout lines
Scrub with a stiff grout brush
Wipe away dirty water with a damp cloth
Apply a baking soda and water paste to stained grout
Spray vinegar over the paste
Let it fizz for a few minutes
Scrub the grout lines again
Rinse thoroughly with clean water
Dry the area with a clean towel
Apply oxygen bleach for deeper stains
Let it sit according to the product directions
Scrub and rinse well
Seal the grout after it dries completely