Over time, grout becomes dirty and discolored—the result of colored shampoos, hard water (calcium and lime deposits), soap build-up, or a crack that allows water to reach the wall surface behind the tile so mold and mildew can start to grow. The biggest downfall with tile is the grout itself, especially in shower areas. These real questions and real answers may help you explore and solve the ins and outs of tile grout in a bathroom setting.