Why Won’t My Dishwasher Drain?
Q: My dishwasher won’t drain and there’s standing water at the bottom. What causes this?
A: When a dishwasher doesn’t drain, the cause is usually one of these: a clogged filter, a blocked or kinked drain hose, a clogged air gap, a garbage disposal knockout plug that wasn’t removed, or a drain pump problem. Many causes are simple fixes—but some require a technician.
Below are the most common reasons a dishwasher won’t drain, what you can safely check, and when to call our friendly technicians in yellow.
See more topics in the Dishwasher Help Center.
1. Dirty or Clogged Filter
This is the most common cause of standing water. Food particles, labels, and grease can restrict flow around the filter and sump.
Signs include:
- Water pooled around the filter cover
- Slow drainage
- Bad odors
Safe fix: Remove the filter, wash with warm soapy water, rinse thoroughly, and reinstall flat and locked.
2. Drain Hose Blocked or Kinked
The drain hose carries water from the dishwasher to the sink drain or garbage disposal. If it’s kinked behind the cabinet—or clogged with grease and debris—draining can slow or stop.
Common issues:
- Kinked or crushed hose behind the dishwasher
- Grease/debris blockage in the hose
- Improper routing (no high loop / incorrect installation)
3. Garbage Disposal Knockout Plug Still Installed
If you recently installed or replaced a garbage disposal, the dishwasher inlet knockout plug may still be in place. That will block dishwasher drainage entirely.
Signs:
- Dishwasher won’t drain right after a disposal install
- A hollow “thunk” sound or water backing up during drain
Note: If you’re not comfortable checking this, schedule service—forcing the drain cycle repeatedly can lead to leaks.
4. Air Gap Blocked (If Present)
Some homes have an air gap on the sink or countertop. Food buildup can clog it and prevent draining.
Tip: If you see water coming out of the air gap or hear gurgling during drain, the air gap or hose routing may need attention.
5. Failed Drain Pump
If the drain pump fails, the dishwasher can’t push water out—even if the filter and hose are clear.
Signs include:
- Humming sound but no draining
- Grinding noise (possible debris in the pump/impeller)
- Error codes on the display
6. When to Call Beacon
Call Beacon Services & Appliances if:
- There’s standing water after every cycle
- You hear buzzing, grinding, or the pump runs but won’t drain
- You recently installed a disposal and the dishwasher stopped draining afterward
- The dishwasher stops mid-cycle or repeatedly throws error codes
Our friendly technicians in yellow can diagnose drain pump failures, clogged hoses, and installation issues quickly—and we’ll see how Beacon can help.
More dishwasher troubleshooting: