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How to Make a High Loop in the Drain Hose for a Dishwasher

Nathan McGinty

A properly installed dishwasher can help save you hours of housework time in the kitchen over the course of its life. These appliances work by pulling in water from your home's water supply and then spraying this over the dirty dishes. The dirty water is then pumped out of the dishwasher through a drain hose and into your home's sewer system. Many cities and municipalities now require dishwashers to be installed with a "high loop" (also known as an "air gap") in the drain line. This prevents the dirty water in the washing machine from being inadvertently pulled back into the municipal water system. Making a high loop in the drain hose for your dishwasher is one of the last steps you need to complete before doing your first load of dishes.

Keep your dishes clean with a properly installed dishwasher.
  1. Ensure that you have plenty of room to work on the dishwasher. If it is under the cabinet, you will have to pull it out so that you can access the drain outlet. Turn off any power to the dishwasher circuit.

  2. Slide the compression clamp over the end of the drain hose. Push the drain hose over the outlet fitting. Give it a tug to make sure it is securely in place. Position the compression clamp so that it is over the portion of the drain pipe where it meets the dishwasher outlet. Tighten the compression clamp with a screwdriver.

  3. Run the drain hose to the inlet on the drain plug. Do not attach it yet.

  4. Create the high loop in the drain hose. Exactly how high it needs to be will be determined by your municipal codes. Raise the drain hose to the proper length and secure it in place with a pipe clamp screwed either into the wall or the underside of the counter where the dishwasher is installed.

  5. Slide another compression clamp over the free end of the drain hose.

  6. Trim the drain hose to the right length if needed.

  7. Slide the other end of the hose onto the sink drain inlet. Push the compression clamp down until it is over the part of the hose that connects to the drain inlet. Tighten with the screw.

  8. Push the dishwasher back into its original location. Restore power to the dishwasher circuit. Do a test wash and keep an eye on the drain hose. Tighten the compression fittings if necessary.