Grout cannot be removed with hot water. Unfortunately, we use concrete and grout to construct larger sewer lines. Because grout hardens in water, you may need to hire a licensed plumber with powerful sewer and drain cleaning technology to clear the line. If the line is made of plastic, you might be able to break it up and push it down to a larger line. If your pipes are steel, however, removing the grout may be impossible unless it is a very thin layer. If there is a lot of grout, it may come loose and clog another line. It is sometimes necessary to disassemble floor drains and other lines. Unfortunately, there is no simple solution to this drain issue. After removing the bathtub trap, try snaking the line. If that fails, a few feet of the line may need to be replaced.