Q: My new kitchen is going to have a large island with my double-bowl sink in it. The young plumber and my contractor want to use some newfangled thing that just fits under the cabinet. They call it ...

N H R A rules state that the loop must be installed no more than 6 inches behind the front U-joint. If you don't mind more holes in the floor, it's a good idea to install one in the rear as well. See ...