1 tsp household
1/4 cup hydrogen peroxide
3/4 cup water
Combine well in
bowl. Pour small amounts onto grout, or saturate towel and
press to grout on a wall, so grout is saturated with the solution.
Scrub with stiff bristled brush (being careful to check that
tile cannot be scratched. Allow to sit for several minutes
then rinse well with warm water. Repeat if needed.