The short answer

Dishwasher draining depends on the hose route, connection point, sink or disposer drain, and the local installation rules. A high loop and an air gap are not interchangeable descriptions. If water appears at the sink, air gap, or dishwasher after a cycle, inspect the complete path before assuming the pump has failed.

Read the arrangement

Visible arrangement What to document Common question
Hose rises under the counter Highest point and support Is the loop actually high enough for the installation?
Countertop air gap Two hose connections and cap condition Is the small fitting or the downstream drain blocked?
Hose enters a disposer Inlet knockout and clamp Was the inlet opened when the disposer was installed?
Hose enters a sink tailpiece Adapter, clamp, and drain position Is the connection permitted and free of a low sag?
Water remains in the tub Filter, pump, hose, and drain path Is the symptom a blockage rather than backflow?

Before touching a connection, switch off the dishwasher and protect the cabinet base. Do not run repeated cycles to “test” a leak. A drain hose can hold dirty water, and a loose clamp can turn a small symptom into cabinet damage.

When a part replacement is premature

If the air gap spills, inspect its cap and hose path. If the disposer connection was recently changed, verify the inlet opening and clamp. If the sink itself drains slowly, the shared drain may be the actual restriction. A new dishwasher pump cannot correct a blocked downstream drain.

Limits

This guide does not substitute for local plumbing code or a manufacturer installation manual. Hidden cabinet leaks, damaged wiring, or a persistent sewage odor should be handled professionally.