Q In a kitchen I'm building for a client, the dishwasher drain line would need to pass through a drawer cabinet to connect to the sink drain. The waste line for the sink passes under the floor directly below the dishwasher. Is there any problem with running the dishwasher drain directly into the waste line?
A Mike Casey, a licensed plumbing contractor and co-author of responds: Whenever possible, it is always best practice to connect the dishwasher drain hose to the kitchen sink drain. Most drawer cabinets have a 3-inch to 4-inch space below the drawers, or space at the back of the cabinet behind the drawers, where the hose can be located.
to read the full article.