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Why is my dishwasher not draining? Causes and fixes

By: Reliable Parts • July 2026

A dishwasher that won’t drain is most often caused by a clogged filter or sump screen, a blocked drain hose, a clogged air gap, or a failed drain pump. Food debris and grease build up in the filter over time and are the single most common cause. Check and clean the filter first, then inspect the drain hose and pump.

Need step-by-step instructions for your specific brand and model? Visit our DIY Repair Guide and filter by appliance and brand.

Safety information

Always disconnect power at the breaker before opening any dishwasher panel. Capacitors in the control board can retain a charge. Standing water in the sump is the dishwasher’s water — not potable — and may contain detergent residue and food debris. Wash hands after working in the sump.

Most common causes

  1. Clogged filter or sump screen — the most common single cause. Food debris and grease build up in the fine mesh and block drainage.
  2. Blocked drain hose — the corrugated hose between the dishwasher and the sink drain or garbage disposal collects sludge over time.
  3. Clogged air gap (if installed) — the small chrome cylinder on the countertop next to the faucet. Debris pushed up from the dishwasher accumulates inside.
  4. Failed drain pump — if the motor is humming but no water moves, the pump impeller is broken or jammed.
  5. Garbage disposal knockout plug not removed — on new disposal installations, the plug in the dishwasher inlet must be knocked out, or the dishwasher cannot drain at all.
  6. Faulty check valve in the drain pump — prevents drained water from flowing back into the tub but can stick closed and block normal drainage.

Step-by-step diagnosis

  1. Unplug the dishwasher or turn off power at the breaker.
  2. Remove the lower dish rack. The filter is at the bottom of the tub, in the center, under the lower spray arm. Twist counterclockwise to remove it. Rinse it thoroughly under hot water and scrub with a soft brush.
  3. Inspect the sump (the area beneath where the filter sat). Remove any food debris or hard items. Some models have a fine sump screen — lift and clean it too.
  4. Disconnect the drain hose from the sink drain or garbage disposal. Run water through it from a faucet to verify it’s clear. A blocked hose will resist water flow.
  5. If your dishwasher uses an air gap on the counter, unscrew the cap and clear any debris from inside.
  6. If a new garbage disposal was recently installed, confirm the inlet knockout plug was removed. It looks like a thin metal disc inside the disposal’s dishwasher inlet.
  7. Reconnect everything, restore power, and start a short cycle. Listen at the end of the cycle for the drain pump. A humming pump that doesn’t move water indicates a failed or jammed impeller. A silent pump indicates an electrical failure (control board, drain pump motor, or wiring).

Replacement parts to consider

Common parts for a no-drain condition: filter assembly, drain pump, drain hose, air gap, check valve. Enter your dishwasher’s model number on reliableparts.com to see the exact parts for your specific model.

Related FAQs

How do I drain a dishwasher full of standing water?

Towel out as much standing water as you can reach. For the deeper water under the filter area, use a wet/dry vacuum or a turkey baster to remove it before disassembling the filter.

Why is there a small amount of water in my dishwasher all the time?

A small puddle (a half-cup or less) of clean water in the sump after a cycle is normal and is designed to keep the pump seal lubricated. Standing dirty water or more than a cup of water indicates a drain issue.

Can a clogged garbage disposal cause my dishwasher not to drain?

Yes. If the disposal is clogged or has standing water inside, the dishwasher cannot drain into it. Run the disposal with the faucet on for 30 seconds before starting the dishwasher to confirm the disposal is clear.

How often should I clean my dishwasher filter?

Every 1-2 months under normal use. Heavy use, or pre-rinsing dishes less aggressively, requires more frequent cleaning. A neglected filter is the single most common cause of drain and clean-quality issues.

How long does a dishwasher drain pump last?

Most dishwasher drain pumps last 7-10 years. Frequent debris in the sump shortens that lifespan because the impeller wears against grit. Replacing the pump is a moderate DIY job that takes 60-90 minutes.