How to Hook up a Dishwasher Drain to a Garbage Disposal

A dishwasher drain line may be hooked up to a garbage disposal for the water to drain out of the kitchen drain line. There are two types of installation: One includes the use of an air gap to add extra air pressure in drainage and the other does not use an air gap. For replacement dishwashers, you may use all existing holes in the cabinet for water, electrical and drain lines.

Step 1

Turn power to the kitchen off by turning off the circuit breaker at the breaker box.  Turn off the main water valve under the sink and turn the sink faucets on to drain water out of the lines.

Step 2

Drill a 1 1/2-inch hole in the cabinet wall closest to the kitchen sink near the floor level for a new installation.  If this is a replacement dishwasher, use the existing holes.

Thread the dishwasher drain hose through the hole while leaving the half-inch end that connects to the dishwasher in the opening of the cabinet near the backside of the dishwasher where the drain line connects. 

Step 3

[Remove the garbage disposal knockout plug](https://homesteadycom/video-7508253-remove-garbage-disposal-knockout-plughtml) by turning it counter-clockwise and pulling it off.  Connect the water drain line to the garbage disposal tee that the plug came off with a large spring clamp or an adjustable metal band.

To use a metal band, slide it over the hose end first, fit the hose on the stem and tighten its screw with a flat screwdriver. 

Step 4

Hammer a nail into the rear of the kitchen cabinet at least 20 inches from the floor, and loop the extra length of the dishwasher drain line over the nail.  This will eliminate the need for an air gap in dishwasher installation.

Step 5

Connect the other end of the drain hose to the dishwasher after making electrical and water connections.  Turn the electricity and water back on and test the dishwasher.

Things You Will Need

  • Dishwasher drain hose
  • Drill
  • Spring clamp or metal tension clamp
  • Flat screwdriver
  • Hammer
  • Nail


  • If the dishwasher drain hose is not long enough to raise at least 20 inches off the floor, or if there is not enough space in the cabinet, an air gap installation is needed. For installation with an air gap, connect the drain hose to the bottom of the air gap in the same manner as above. Connect a rubber hose from the side tee of the air gap to the tee in the garbage disposal with a spring clamp or an adjustable metal band.
  • Keeping the drain hose from actually touching the hole in the side of the kitchen cabinet will minimize vibration when the dishwasher drains and keep connections tight.
  • Before anchoring the dishwasher into its cabinet space it is recommended to activate the dishwasher and run through one complete cycle so that any water leaks may be observed and corrected.

About the Author

Mary Lougee has been writing for over 10 years. She holds a Bachelor's Degree with a major in Management and a double minor in accounting and computer science. She loves writing about careers for busy families as well as family oriented planning, meals and activities for all ages.

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