How to Make Dishwasher Drain Hose Connections

Drain Connection With Air Gap and Garbage Disposal

If an air gap fitting is used, there will be two lengths of drain hose: the factory drain hose on the dishwasher, which runs from the dishwasher to the smaller of the two tailpieces on the air gap, and a 7/8-inch (inside diameter) hose that runs from the other tailpiece on the air gap to the dishwasher nipple on the garbage disposal. 

1. Connect Hose to Air Gap

   Using a utility knife, cut down the dishwasher drain hose from the dishwasher so it is just long enough to reach the smaller tailpiece on the air gap fitting mounted on the countertop or sink deck. Connect the end of this hose to the air gap using a hose clamp.

2. Connect Hose to Garbage Disposal

   The large end of the air gap is then connected to the garbage disposal with a 7/8-inch rubber hose. Both ends of the hose are connected with hose clamps (one on the air gap and one on the garbage disposal inlet nipple).

   Warning

   When making the connections, make sure the 7/8-inch hose does not have any kinks. Kinks will restrict the flow of drain water and may cause a blockage over time. If it is too long, it may need to be trimmed down to size to prevent kinking. 

Drain Connection With Air Gap (But No Garbage Disposal)

When connecting a dishwasher drain with an air gap but no garbage disposal, the drain hose is indirectly tied to the sink drain through the air gap.

1. Connect Hose to Air Gap

   First, connect the dishwasher drain hose to the small side of the air gap, mounted on the countertop or sink deck. You may need to use some force to slide the hose onto the air gap fitting.

2. Connect Hose to Drain Pipe

   Then, using a 7/8-inch rubber hose, hook up the larger side of the air gap to the Y-branch tailpiece on the sink drain. If your drain doesn't already have this tailpiece, you'll need to install one. Y-branch tailpieces are available in two sizes, so get the size that fits the 7/8-inch hose running from the air gap.

3. Secure With Hose Clamps

   Use hose clamps to connect both ends of the hose to their tailpieces. Before you clamp the hose in place, make sure there are no kinks in the tubing. Too-long hoses can be trimmed down to size.

Drain Connection Using High Loop to Garbage Disposal

Before installing this dishwasher drain connection, ensure the local building codes allow for the high loop method instead of an air gap. In some areas, the high-loop method may not be permitted.

1. Prepare the Drain Hose

   Pull as much of the drain hose as possible from behind the dishwasher. You will need this extra drain hose to create the high loop before connecting the dishwasher hose to the garbage disposal.

2. Loop the Drain Hose

   Pull the dishwasher drain hose up and strap it as high as possible under the sink. This high loop will help prevent wastewater from siphoning back into the dishwasher from the garbage disposal. A large pipe clamp or piece of flexible pipe strapping can secure the hose to the underside or wall near the countertop. 

3. Connect the Hose

   Connect the dishwasher drain tube directly to the garbage disposal with hose clamps. To make the transition from the hose to the garbage disposal, you may need a dishwasher connector fitting. One end of the connector attaches to the smaller drain hose, and the other end has a larger 7/8-inch fitting that attaches to the garbage disposal.

   Tip

   If the dishwasher isn't draining correctly after connecting the hose, check for kinks in the hose and clogs in the drain basket or hoses. Also, check the air gap cylinder, which is the part next to the drain pump that connects the drain hose. If it's dirty or clogged, that can also cause draining issues.

Drain Connection Using High Loop Directly to Drain

Once again, check the local building codes to ensure the high loop method is legal in your area.

1. Loop the Drain Hose

   Pull as much drain line as possible from behind the dishwasher, loop it as high as possible under the sink, and strap it in place. This will prevent wastewater from the sink drain from siphoning back into the dishwasher.

2. Attach Hose to Sink Drain

   Attach the end of the dishwasher drain line to the Y-branch tailpiece on your drain, securing it with a hose clamp. Y-branch tailpieces that match the size of your dishwasher drain hose can be purchased.