Dishwasher Not Draining: Causes and Fixes

Standing water in the bottom of your dishwasher almost always comes down to three things: a clogged filter, a kinked or blocked drain hose, or a problem at the garbage disposal connection. Start with the fastest checks. Pull out the bottom rack, twist out the filter at the tub floor, and rinse it clean. Then run your garbage disposal for 30 seconds, because a clogged disposal blocks the dishwasher's drain path too. If the water still sits there after a Cancel or Drain cycle, work through the checks below in order.

Clean the Filter

The filter catches food particles so they do not reach the pump. When it clogs, water cannot leave the tub fast enough, and dirty water sits at the bottom after every cycle.

• Clogged filter screen — Remove the bottom rack. Twist the cylindrical filter counterclockwise and lift it out, along with the flat mesh screen under it. Rinse both under hot running water and scrub gently with a soft brush or old toothbrush. Do not use wire brushes or harsh chemicals that can damage the mesh.
• Filter not seated properly — A filter that is sitting crooked lets food slip past it into the pump area. After cleaning, drop it back in, twist clockwise until it locks, and confirm it sits flat.
• Food and grease buildup in the sump — With the filter out, wipe the sump area underneath with a damp cloth to remove sludge. This is also a good time to check for glass shards, bones, or labels that fell through.
• How often to clean — If you scrape but do not rinse dishes, clean the filter every two to four weeks. Households that rinse well can go a month or two between cleanings.

Run the Garbage Disposal

Most dishwashers drain through the garbage disposal. If the disposal is jammed or full of food waste, dishwasher water backs up into the tub.

• Clogged or jammed disposal — Turn on the cold water and run the disposal for about 30 seconds to clear food waste from the shared drain path. Then run the dishwasher's Cancel or Drain cycle and see if the water leaves.
• Sink draining slowly — If your kitchen sink also drains slowly, the blockage is in the shared sink plumbing, not the dishwasher. Clear the sink drain first with a plunger or by cleaning the trap.
• Disposal never runs — If the disposal is dead, food sits in it permanently and blocks the dishwasher drain. Fix or replace the disposal before troubleshooting the dishwasher further.

Check the Knockout Plug (New Disposal Installs)

This is the single most common cause of a dishwasher that stopped draining right after a new garbage disposal was installed.

• Knockout plug still in place — New disposals ship with a plastic plug sealing the dishwasher inlet. If the installer forgot to remove it, water cannot enter the disposal at all. Disconnect the dishwasher drain hose from the disposal nipple, put a screwdriver against the plug inside the nipple, tap it with a hammer to knock it in, then reach into the disposal and pull the plastic piece out.
• How to confirm — Look inside the disposal's dishwasher nipple with a flashlight. If you see solid plastic instead of an open hole, the plug is still there.
• Reconnect tightly — Push the drain hose fully back onto the nipple and tighten the clamp. A loose hose leaks under the sink.

Inspect the Drain Hose

The flexible hose from the dishwasher to the sink drain is a classic clog and kink spot, especially right after the dishwasher was pulled out for installation or flooring work.

• Kinked or crushed hose — Pull the dishwasher out a few inches or open the under-sink cabinet and follow the hose from the dishwasher to the disposal or sink drain. Straighten any sharp bends or kinks. The hose should curve gently with no flattened sections.
• Clogged hose end — Disconnect the hose at the disposal or sink end and check for a plug of grease and food debris. Flush it with hot water or clear it with a bottle brush.
• Wrong hose height — The hose must rise up high under the countertop, about 30 centimeters (12 inches) above the floor, before dropping down to the drain. A hose that droops low lets sink water flow back into the dishwasher and can cause siphoning problems.
• Frozen hose — In an unheated garage or vacation home in winter, the hose can freeze. Thaw it with warm towels and keep the space heated.

Check the Air Gap

The air gap is the small chrome or plastic cylinder on the back edge of your sink. It prevents dirty sink water from flowing back into the clean dishwasher, and it clogs easily.

• Clogged air gap — Pop off the air gap cap and look inside for food debris. Scoop it out with your finger or a small brush, then run the disposal and a drain cycle. Water spurting from the air gap onto the counter during draining is a sure sign it was blocked.
• Missing air gap with no high loop — If your sink has no air gap, the drain hose itself must form a high loop secured up under the countertop. If the hose just runs flat along the cabinet floor to the drain, sink water will keep flowing back into the tub.

Check the Drain Pump and Check Valve

If water reaches the pump but goes no further, the pump or the one-way valve in the drain path may be jammed or dead.

• Listen to the pump — Start a Cancel or Drain cycle and listen under the dishwasher. A healthy pump makes a steady humming or whirring sound. Total silence suggests no power to the pump or a dead pump motor. A loud grinding or rattling suggests something hard, like glass or a bone fragment, is jamming the impeller.
• Jammed impeller — With power off at the breaker, you can sometimes reach the pump area through the filter opening and feel for debris. Remove anything you find. If the impeller blades are broken, the pump needs replacement.
• Stuck check valve — A small one-way flap in the drain path stops dirty water from flowing back into the tub. Food debris can glue it shut. This is usually serviced along with the pump assembly.
• No DIY pump replacement for most people — Reaching the pump means pulling the dishwasher out and tipping it. Note the symptoms you found and hand them to a technician.

Try a Reset and Check the Cycle

Sometimes the machine is fine and the electronics just need a clean restart, or the cycle was interrupted before the drain step.

• Run Cancel or Drain — Press and hold Cancel, or select the Drain option if your panel has one, and let it run its full course. Some machines need a full uninterrupted drain attempt.
• Power reset — Turn the dishwasher off at the breaker for one minute, then restore power and run a short cycle. This clears temporary control glitches.
• Cycle was interrupted — If the door was opened mid-cycle or power flickered, the machine may never have reached the drain step. Close the door firmly and let a complete cycle run.
• Too much detergent — Excessive suds can confuse the water-level sensor and interfere with draining. Use only automatic dishwasher detergent in the amount your manual recommends, and never use regular dish soap.

Prevent Future Drain Problems

A dishwasher that drains well today can clog again in a few months if food and grease keep building up. A small maintenance routine keeps the drain path clear.

• Scrape plates before loading — Scrape large food pieces into the trash. You do not need to rinse, but bones, seeds, labels, and large chunks should never go in.
• Clean the filter on a schedule — Set a monthly reminder. A two-minute rinse under hot water prevents the slow buildup that eventually blocks drainage.
• Run hot water first — Run the kitchen tap until the water is fully hot before starting the dishwasher. Hot water dissolves grease in the drain hose instead of letting it cool and solidify there.
• Run a cleaning cycle monthly — Run the dishwasher empty on the hottest cycle with a cup of white vinegar on the top rack or a dishwasher cleaner. This dissolves grease in the pump, hose, and filter housing.
• Check the air gap twice a year — Pop the cap and clear any debris before it becomes a full blockage.