Why Is My Dishwasher Not Draining?
Standing water in your dishwasher is almost always caused by a clogged filter, blocked drain hose, or faulty pump. Here's how to diagnose and fix it.
By Tyler
If you're opening your dishwasher to find standing water at the bottom, the most common culprit is a clogged filter or blocked drain hose — and in many cases, it's something you can fix yourself in 10 minutes. If the water won't budge after checking those, it's likely a pump or drain valve issue that needs a technician.
The Most Common Reasons a Dishwasher Won't Drain
1. Clogged Filter
Most modern dishwashers have a cylindrical filter at the bottom of the tub that catches food debris. If you've never cleaned it, there's a good chance it's the problem.
To check it: remove the bottom rack, twist out the filter (usually counterclockwise), and rinse it under warm water. Use a soft brush to clear any stuck debris. Reinstall and run a short cycle to see if it drains.
This is the #1 cause of drainage problems we see, and most homeowners don't even know the filter exists.
2. Blocked or Kinked Drain Hose
The drain hose runs from the dishwasher to either your sink drain or garbage disposal. If it's kinked, clogged, or not elevated properly, water can't exit.
Pull the dishwasher out slightly (or check under the sink) and look for obvious kinks in the hose. If it connects to the garbage disposal, make sure the disposal's knockout plug was removed when it was installed — this is a surprisingly common oversight that causes drainage failure from day one.
3. Clogged Garbage Disposal
If your dishwasher drains into the garbage disposal and the disposal itself is full of sludge, the dishwasher water has nowhere to go. Run the disposal with water for 30 seconds before starting a wash cycle. If it's partially blocked, that may be all you need.
4. Blocked Air Gap
Some installations include an air gap — a small chrome cylinder mounted on the countertop near the faucet. It prevents sink water from backflowing into the dishwasher, but it can get clogged.
Pop off the cap and clean out any debris inside. This is a quick fix that's often overlooked.
5. Faulty Drain Pump or Solenoid
If none of the above fixes it, the drain pump or drain solenoid may have failed. The pump pushes water out; the solenoid opens the drain valve. Either can fail with age.
You'll often hear the dishwasher trying to drain (a humming or buzzing sound) but no water actually moves. This is a repair that requires opening up the machine — best left to a technician.
6. Control Board or Cycle Issue
Occasionally the dishwasher stops mid-cycle due to a power interruption or software glitch, leaving water in the tub. Before assuming there's a mechanical problem, try running a new cycle from the start. If it drains normally, it was likely a one-time cycle interruption.
Step-by-Step: What to Check First
- Clean the filter — twist it out, rinse it, put it back
- Run the garbage disposal for 30 seconds
- Check the drain hose for kinks under the sink
- Check the air gap if you have one — remove the cap and clean it out
- Run a new cycle to see if the issue resolves
- Listen during the drain phase — is the pump humming? Silence usually means an electrical issue; humming with no water movement points to a blockage or pump failure
When You Should Call a Technician
If you've worked through the checklist above and the dishwasher still won't drain, it's time to call in help. Pump and solenoid replacements, control board issues, and internal blockages require disassembly and aren't worth attempting without experience — especially on newer machines where the wrong move can cause additional damage.
I work on dishwashers from all major brands — Bosch, KitchenAid, Whirlpool, Samsung, GE — across Greater Boston and the North Shore. Most repairs can be diagnosed and completed in a single visit.
Frequently Asked Questions
Is it safe to use my dishwasher if it's not draining fully? Not ideal. Standing water breeds bacteria and can start to smell quickly. It also puts strain on the pump motor if it's running against standing water. Hold off on using it until the issue is resolved.
Why does my dishwasher drain fine sometimes but not others? Intermittent drainage is usually a partially clogged filter or a failing pump that works when the load is light but can't handle a full cycle. Clean the filter first — if the problem persists, the pump is likely on its way out.
How do I know if my dishwasher drain pump has failed? If you can hear the machine trying to drain (a humming noise) but no water moves, the pump may be seized or the impeller may be jammed. If you hear nothing at all during the drain phase, it could be an electrical issue with the pump motor or control board.
My dishwasher is new and already not draining — what's going on? On new installs, the most common cause is a garbage disposal knockout plug that was never removed. The dishwasher drain hose connects to the disposal, and that plug blocks it completely. This is an easy fix — just knock out the plug from inside the disposal.
How much does it cost to fix a dishwasher that won't drain? If it's just a dirty filter or a kinked hose, it costs nothing. A drain pump replacement typically runs $150–$300 in the Greater Boston area depending on the brand and part availability.
Standing water in your dishwasher isn't something you have to live with. Book a repair visit and I'll have it diagnosed and fixed — usually the same day.