How to Connect a Dishwasher Drain to a Garbage Disposal

Begin by ensuring your safety and preparing the work area. Go to your home's electrical panel and turn off the circuit breakers that supply power to both the garbage disposal and the dishwasher. To be certain the power is off, try flipping the garbage disposal switch at the wall. Clear out all items from under the sink cabinet to create ample space to work. Place a bucket and some old rags or paper towels under the sink to catch any residual water.

If your garbage disposal is new, it will have a sealed dishwasher inlet port. You must remove the internal plug before connecting the hose. Locate the angled inlet nipple on the upper side of the disposal body. Insert the tip of a flathead screwdriver into the inlet and tap the end of the screwdriver handle firmly with a hammer. You should feel and hear the plug pop loose and fall into the main grinding chamber of the disposal. If the disposal is already installed, this can be done from the side; if it's uninstalled, lay it on its side on a towel for better access and leverage.

With the power confirmed off, reach through the sink drain opening into the garbage disposal's grinding chamber. Feel for the small, circular piece of plastic that you just knocked out. Retrieve it with your fingers. If it is difficult to grasp, you can use a pair of needle-nose pliers to grab it and pull it out. It is critical to remove this piece to prevent it from clogging the drain or damaging the disposal blades.

To prevent dirty water from the sink from flowing back into your dishwasher, you must create a 'high loop' with the drain hose. Take the corrugated drain hose from the dishwasher and pull it up as high as it will go under the sink, ideally touching the underside of the countertop. Secure the hose at this high point to the back or side wall of the cabinet using a pipe strap or a heavy-duty zip tie. This ensures that the water level in the sink would have to be extremely high to backflow into the hose.

First, slide the hose clamp over the end of the dishwasher drain hose. Next, push the end of the hose firmly onto the garbage disposal's plastic inlet nipple that you cleared in the previous step. The hose should slide on at least 1/2 to 3/4 of an inch. Once the hose is in place, position the hose clamp about 1/4 inch from the end of the hose, over the section covering the nipple. Use a flathead screwdriver or a nut driver to tighten the screw on the hose clamp until it is snug and secure.

The final step is to verify your work. Place a dry paper towel or rag on the bottom of the cabinet directly under the new connection. Go back to the electrical panel and restore power to the dishwasher and garbage disposal. Start a 'rinse only' or 'drain' cycle on your dishwasher. As the dishwasher pumps out water, use a flashlight to carefully inspect the hose connection at the disposal for any signs of dripping or leaking. Once the cycle is complete and you've confirmed there are no leaks, run cold water into the sink and turn on the garbage disposal for a few seconds to ensure it operates smoothly.