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Dishwasher Won't Drain: Causes & Fixes

Why is there standing water in the bottom of my dishwasher and how do I fix it?

Standing water in a dishwasher almost always means a clog (in the filter, drain hose, or air gap) or a blocked garbage disposal. Most cases are a 15-45 minute DIY fix; a dead drain pump is the main job that usually needs a pro.

ℹ️ Reference only: For general reference only: AI-assisted and not professional advice. This guide guarantees no result; every situation differs. Verify against the manufacturer, local codes, and a licensed professional before acting, especially for electrical, gas, fuel, plumbing, structural, or roof work. Use at your own risk.

Common causes

• Clogged dishwasher filter at the bottom of the tub, packed with food, grease, and debris (most common)
  Quick check: Open the door, remove the lower rack, and twist out the cylindrical filter. Look for food gunk, grease, glass shards, or paper labels caked in the mesh.
• Garbage disposal drain plug (knockout) still in place after a new disposal install, or disposal full of food (most common)
  Quick check: If you recently installed a disposal, the dishwasher hose connects to it; the knockout plug may never have been punched out. Run the disposal empty and check the dishwasher inlet for the plug.
• Clogged or kinked drain hose between the dishwasher and the disposal/sink drain (common)
  Quick check: Look under the sink for a kink in the corrugated hose; with a bucket ready, disconnect the hose end and check for a soft food clog at the bend where it loops up.
• Blocked air gap (the small chrome cylinder on the countertop next to the faucet) (common)
  Quick check: Pop the cap off the air gap; if water spurts out during a cycle or you see gunk, it's clogged. Water leaking onto the counter during a cycle is the tell.
• Drain hose missing a high loop (and no air gap installed), letting dirty sink water siphon back into the tub (less common)
  Quick check: Confirm the hose rises to just under the countertop before dropping to the disposal; if it runs flat or low with no air gap, backflow can collect water.
• Failed drain pump or a foreign object (glass, seed, bone) jamming the impeller (less common)
  Quick check: After clearing the filter you still hear a hum with no draining, or a buzzing/grinding: the pump or impeller is likely stuck or burned out. This is a repair-tech job on most units.
• Stuck check valve or faulty drain solenoid/valve (less common)
  Quick check: Water drains very slowly or refills after pumping out: the valve that stops backflow may be stuck open or clogged.

How to fix it

1. Run the garbage disposal empty for 10-15 seconds first: the dishwasher usually drains through it, and a full or recently installed disposal (with the knockout plug still in) is the fastest thing to rule out.
2. Turn off the dishwasher at the breaker or unplug it before reaching into the tub or working on the pump: moving parts and water plus electricity don't mix.
3. Scoop out the standing water with a cup and sponge so you can work; lay towels down to catch spills. Wear gloves in case of broken glass.
4. Remove the lower rack, twist out the cylindrical filter (usually a quarter-turn counterclockwise), and rinse it under hot water with an old toothbrush. Clear any visible debris from the sump opening underneath, by hand with gloves, not by reaching blindly toward the impeller.
5. Clean the air gap: twist off the chrome cap and inner cover on the counter, pull out any debris, and rinse. Reassemble.
6. Check the drain hose under the sink for kinks and straighten it. With a bucket and towels ready, disconnect the hose ends and flush them or push a clog free with a long brush.
7. Confirm the drain hose has a high loop fastened up under the countertop, or that an air gap is installed; this prevents siphon-back. Adding a missing high loop is a simple zip-tie fix.
8. Optionally pour a cup of baking soda followed by a cup of white vinegar into the bottom, wait 15 minutes, then run a rinse cycle to help cut grease. This is a mild maintenance step, not a fix for a true clog.
9. Run a short rinse cycle and watch. If it still won't drain after clearing the filter, hose, and air gap, the drain pump or check valve likely needs replacement; that's an appliance-repair-tech job on most units.

DIY or call a pro?

DIY handles the vast majority: filter, air gap, drain hose, disposal, and high-loop checks are all safe with basic tools and the power off. Call an appliance repair tech if the unit still won't drain after everything is cleared; that points to a failed drain pump, check valve, or control board, which means accessing the pump under the tub and disconnecting wiring. On a budget unit, that repair often costs enough that replacement makes more sense.

Tools & parts

• Cup or measuring cup and sponge/towels for bailing water
• Work gloves (broken glass in standing water)
• Old toothbrush or small brush for the filter
• Screwdriver (Phillips and flathead)
• Bucket for catching hose water
• Pliers or nut driver for hose clamps
• White vinegar and baking soda
• Flashlight

Based on: manufacturer guidance (dishwasher owner's manuals: filter cleaning and drain troubleshooting); building-code norms (drain high-loop / air gap requirements under sink); reputable DIY references (general appliance troubleshooting in the spirit of This Old House / Family Handyman / Bob Vila)

This is general guidance for typical US residential dishwashers, not a substitute for your unit's manual or a licensed technician. Models vary; always disconnect power before servicing internal parts, and consult a professional if you're unsure or the problem persists. Information here is general reference only and may be estimated or AI-assisted. It is not professional advice. Verify with a qualified professional before acting, and use it at your own risk. See our Terms & Disclaimer.