Dishwasher Anti Siphon - Air Gaps or High Loops

Dishwasher High Loops

During a home inspection is it very common and expected to see a dishwasher that does not have an anti siphon device installed. Often the high loop is coiled at the bottom of the cabinet or an air gap that was installed has been disconnected and was not reconnected after a new dishwasher was installed.

High loops are one of the easiest ways to prevent food and other contaminates from reentering the dishwasher after the dishes are cleaned. Frequently the hose from the dishwasher is long enough to be used as a high loop but was never mounted to the cabinet.

There are two simple ways to install a high loop hose. You can either use a proper high loop bracket or you can use any type of metallic strapping for pipes or conduit.

Many dishwashers have what appears to be a high loop installed on the side of the dishwasher. This high loop is adequate enough to prevent anything sent down the drain by the dishwasher from re-entering the dishwasher, but it is not adequate enough to prevent a backed up sink from sending dirty water into the dishwasher. The purpose of the high loop and air gap is to prevent any dirty sink water from entering the dishwasher.

Dishwasher Air Gaps

Air gaps can also be used as an anti siphon device, but they are much more difficult to install and will require the skills of a plumber. If an air gap is already installed then connecting to the air gap is a very easy task.

Air gaps can be connected to a garbage disposal or directly to the drain pipe. Since the air gap is above the highest level of the sink there is no way for water to back flow even if the sink is overflowing. If there is a clog in the system the air gap has a cover with a hole in it to direct the excess water. The hole should be oriented towards the sink so that the sink can catch any water that does not properly go down the drain.

If you have any additional questions about dishwasher anti siphons, please contact your home inspector or send us a message.