Why this setup matters
- A drain hose routed too low can allow sink water to move back toward the dishwasher.
- A hose pinched behind the dishwasher, sharply kinked under the sink, or trapped by stored items can restrict drainage.
- Some jurisdictions or installations require an air gap rather than relying only on a high loop.
- A clogged household sink drain, disposer connection, or damaged hose can look like a dishwasher fault even when the dishwasher itself is working normally.
Safe checks in order
- 1
Find the exact installation instructions
- Locate the model number and read the manufacturer installation manual before changing hose height or routing.
- Check local plumbing requirements. Samsung notes that the drain may use an air gap or high loop depending on local regulation, and Whirlpool documents a high-loop height for its applicable models.
- 2
Turn off power before moving the dishwasher
- If the hose cannot be checked without pulling the dishwasher forward, switch off the dishwasher circuit or unplug it where the plug is safely accessible.
- Do not move a hardwired unit or disturb water/electrical connections you are not qualified to handle.
- 3
Inspect the visible drain hose path
- Under the sink, look for crushing, sharp kinks, a low sag, damage, or stored items pressing on the hose.
- If a new installation will not drain, also check whether the dishwasher may be sitting on its own hose.
- 4
Verify the high point or air gap
- Follow the exact manual for where the hose should rise and how it should be secured. Do not copy a height from another brand or model.
- If an air gap is required by local code or the installation instructions, keep it in the system rather than bypassing it.
- 5
Check the household drain side
- Run the sink and confirm it drains normally. A slow or backed-up sink points to a plumbing problem that can affect the dishwasher.
- If connected to a disposer, use the disposer manufacturer instructions for a new dishwasher connection; do not drill or remove plugs unless the documented installation procedure calls for it.
- 6
Run one supervised test only after everything is secure
- Restore power only after the hose is supported, connections are dry, and nothing is pinched.
- Watch the sink cabinet and floor during a short cycle/drain. Stop immediately if water leaks or the drain backs up.
Brand, model, and code differences
- Whirlpool documents a high drain loop for applicable models and says an air gap should be used when the loop cannot meet its specified installation height.
- Samsung says the drain hose should use an air gap or high loop as local regulations require and warns that a newly installed dishwasher can pinch its own hose.
- Air-gap requirements are set partly by local plumbing codes, not just appliance brand.
- Drain-hose diameter, maximum length, extension rules, disposer connection, and mounting points are model-specific.
Actions not recommended
- Do not bypass a required air gap or local plumbing requirement.
- Do not drill countertops, alter hard plumbing, or open electrical junction boxes unless you are qualified and the installation instructions require it.
- Do not force, splice, tape, or clamp a damaged drain hose as a permanent repair.
- Do not use a universal hose-height number when the exact model instructions specify something different.
When to stop and get help
- The sink or household drain backs up or repeatedly clogs.
- The dishwasher must be removed and hardwired, gas, cabinetry, or fixed plumbing work blocks safe access.
- The hose is damaged, leaking, frozen, or cannot be routed within the manufacturer limits.
- The dishwasher still will not drain after the visible installation path and household drain are confirmed correct.
Official manufacturer sources
- Whirlpool Product HelpChecking the Drain Loop Height ↗
- Samsung SupportSamsung dishwasher is not draining ↗
Reviewed: September 22, 2026.