A clog in your kitchen sink drain could cause dirty water to back-flow into the dishwasher and contaminate the inside of the washer tub. Some municipalities require you install an air gap between your dishwasher and garbage disposal or sink drain to avoid such an occurrence. You can install an air gap in a single afternoon without the help of a plumber. Dishwasher air gap kits are available with everything needed for the air gap, but not the additional hose required to attach the gap to either the sink drain or the disposal.

Things You Will Need:

Flat-blade screwdriver
Masking tape
1 1/4-inch hole saw
Cordless power drill
7/8-inch inside-diameter drain hose
Hose clamps


1. Look for an additional hole precut in your sink next to the faucet base. If you have a hole, it will be covered with a round cap. You can pry the cap from the sink with a flat-blade screwdriver or remove the lock nut beneath the sink holding the cap in place. If you don’t have an extra sink hole, you must create a hole for the air gap in the counter top.

2. Tape off an area of counter top directly behind the sink at least 2 inches square. If you have a double-bowl sink, tape behind the side of the sink closest to the dishwasher or tape behind the side that holds the garbage disposal. The masking tape will protect the counter top from damage.

3. Attach a 1 1/4-inch diameter hole saw to a cordless power drill. Position the saw over the tape. Drill through the counter top to create a hole for the air gap. Remove the tape remnants.

4. Access the area beneath the sink. Insert the air gap up through the hole you created in the counter top or the hole in the sink. Have an assistant thread the air gap lock nut onto the threads of the air gap, tightening the lock nut against the counter top.

5. Loosen, but do not remove, the screw on the hose clamp that holds the dishwasher drain hose to either the garbage disposal or the sink drain. Pull the drain hose off the sink drain or garbage disposal and slide it over the smaller of the two legs on the air gap. Secure the dishwasher drain hose to the air gap by tightening the hose clamp screw.

6. Cut a length of 7/8-inch inside-diameter drain hose to fit between the air gap and the sink drain or the garbage disposal. Slide a hose clamp onto each end of the new drain line. Attach one end of the drain line to the remaining leg on the air gap and tighten the hose clamp screw to hold it in place. Attach the remaining end of the drain line to either the sink drain or garbage disposal and secure it with the remaining hose clamp.

7. Slip the air gap beauty cover over the plastic portion of the air gap on top of the sink or counter top. Rotate the beauty cover where the vent slots point toward the sink.