The drain hose is an integral component of a dishwasher because it carries used water from the appliance to an approved drain connection.
The connection of this hose will depend on the type and model of the dishwasher as well as the plumbing setup around the appliance.
An important factor that affects the drain hose operation is its length.
So, how long can a dishwasher drain hose be?
The Correct Dishwasher Drain-Hose Length
There is no universal permitted hose length. Use the installation instructions for your exact dishwasher, including the maximum total length, minimum and maximum connection height, approved extension kit and hose diameter. A longer or thicker hose is not automatically an acceptable substitute.
For example, Bosch installation manual 9001831461_A permits its specified extension kit and limits the total drain-hose length, including the section to an air gap, to 150 inches (380 cm). That is an example for the models covered by that manual, not a limit that applies to every dishwasher.
High Loop and Air Gap Are Different
A high loop is a drain hose secured at a specified elevated position. An air gap is a separate backflow-prevention fitting that provides a physical break between the dishwasher discharge and the drain connection. They are not two names for the same thing.
Follow both the dishwasher’s installation instructions and local plumbing requirements. Where an air gap is required, a high loop alone is not a substitute.
How to Plan the Hose Route
Identify the approved drain connection, which may be at a disposal or a suitable sink-drain fitting. Measure the actual route, including the required rise, bends and air-gap connection where applicable. Do not include unrelated sink plumbing in the dishwasher-hose measurement.
Use the supplied hose and any extension specified by the manufacturer. Avoid kinks, crushed sections and unsupported makeshift joints. Do not cut a hose or molded connector unless the installation instructions expressly allow it.
A qualified installer can check the available route against the permitted length and height and ensure the connection is secure. If the route exceeds the manual’s limits, change the installation plan rather than adding an arbitrary four to six feet of hose.
Related reading: Dishwasher water efficiency and dishwasher and disposal circuit considerations.
