Hi...I'm no plumber but have done bits and pieces - I know my limitations. I have a problem with a shower waste in a friends very old guest house. In one room only the 4" waste pipe is above floor level and runs across the room. They've converted the room to a bathroom with shower but obviously the shower waste is now below the 4" waste. No room to raise the shower (low ceiling) and not a lot of room under the floor (room below). Is there some sort of pump that they can use to pump the shower waste "up" to a boss in the 4" pipe? I attach a diagram that may help explain what I mean.