The grout in my bathroom floor seems to have been "bleached" in various spots over the last 10 years. Lots of different colors going on here and it kind of bugs me. It was all darker gray when the tile was newly installed. I am quite sure the grout was sealed...but there are many areas where it looks like it has been bleached white or lighter. I don't use bleach on the tile- so not sure how this happened. I just want to know- is it possible to get all the grout back to the original gray color? Would we have to have all new grout installed or can it be "stained" a new uniform color? I have a box of the original grout material in the garage so I know what manufacturer and color it was originally. I have tried cleaning it with mild cleaner and a small brush many times. I am certainly no tile or grout expert and would appreciate some advice. Thanks!