Dishwasher high loop install

The high loop should be installed as close as possible to the underside of the cabinet for maximum effectiveness. The connection should be before upstream of the P-trap on your sinks plumbing. A connection should never be at the P-trap or after downstream of the trap this leads to backflow and sewer gases coming from the drain lines. Avoid connections to garbage disposals. Disposers could potentially send dirty water back into your dishwasher when they are turned on. If you notice standing water at the bottom of your dishwasher between washing cycles, chances are the drain hose is not elevated enough.

There are two reasons why dishwashers must have a high loop. First, it's paramount to ensure that wastewater drains properly during the drain cycle and to prevent siphoning. The second reason is to prevent contaminated water from back flowing into the dishwasher from the garbage disposal or sink drain.

Pro Tip: While there are new dishwashers that have a high loop built in, the installation instructions from various manufacturers all say to install the high loop underneath the sink. Installing an air gap in a drain line is the only surefire way to prevent back siphoning. The high loop is shown properly fastened to the underside of the countertop as needed. An air gap is a vent that goes up through the top of the sink or countertop.

An air gap is optional, but not needed with a properly installed high loop drain line. In the photo below left at a San Antonio area Home Inspection, it can be seen that there is no high loop drain line as needed. A high loop should always be installed with the dishwasher drain line to prevent backflow of waste water to the dishwasher.

The high loop should be fastened, secured to the bottom of the countertop. In the photo above right the dishwasher drain line was properly installed with a high loop and securely fastened to the underside of the countertop which also allows for the proper slope of the drain to the disposal.

In conclusion, high loop drain lines are an absolute neccessity with the installation of a dishwasher. If a drain line was incorrectly installed for a dishwasher, it can easily be corrected. Call for more info You're right Joe the high loop drain line is a necessity to prevent cross contamination into the water supply.

I would say about half of the houses I inspect have the high loop installed properly. I'm glad you posted this, most people don't think about this but it is very easy to fix. ICC Member Click above for more Info:. Navigation 1. Because the top of the loop is located above the flood level of the dishwasher, it makes it unlikely that drain water can be siphoned back into the dishwasher.

The high loop method is not as reliable as an air gap, but it can help to prevent contaminated water from being drawn back into the dishwasher. Where allowed, the high loop method frees up a sink mounting hole that can be used for a soap dispenser , water filtration , or instant hot water dispenser.

An air gap connection was once the preferred method of connecting a dishwasher drain, though its practicality has faded. An air gap is a small metal or plastic fitting that is installed on the countertop or sink and usually has a decorative cap.

The device has two hose fittings on its underside, below the sink or countertop. The incoming dishwasher drain hose connects to one fitting, while a secondary hose runs from the other fitting to the kitchen sink's drain pipe or garbage disposer. The air gap works by allowing fresh air into the drain hose if there is a backup causing negative pressure. This eliminates any suction force that can draw water back into the dishwasher chamber.

Air gaps are designed to fit into an existing mounting hole on the top of the sink or they can mount to any type of countertop. They are available in a variety of finishes to match your faucet and sink. While using an air gap connection is still doable, it is no longer the preferred method and is not as practical as using a high loop or check valve.

The dishwasher drain hose will always run from the dishwasher up to the air gap or high loop first, then it runs back down to connect to the drain system. How you connect to the drain system depends on whether or not you have a garbage disposal installed under your sink. When there is a garbage disposal installed, the dishwasher drain line should run down from the air gap or high loop and connect to a side nipple on the disposal, where it connects with a hose clamp.

Do not bypass the garbage disposal if it is present. By draining the dishwasher through the disposal, larger pieces of food residue will be captured in the disposal, where they can be ground up when the garbage disposal is next used. When there is no garbage disposal present, the dishwasher hose should run down from the air gap or high loop and connect to the sink drain by means of a drain tailpiece with a branch fitting.