Why Is My Dishwasher Not Draining?

You open the dishwasher and find an inch or two of murky standing water in the bottom. Before you call a repair tech, work this simple rule: fix it from the outside in, starting with the easiest, most common causes. The majority of draining problems are solved by steps 1–4 below, cost nothing, and take under 30 minutes.

The 7-step ladder: (1) cancel and reset the cycle, (2) clean the filter — a two-minute job that fixes a large share of cases, (3) clear the sump of glass and food debris, (4) run the garbage disposal and check the dishwasher knockout plug, (5) check the air gap cap, (6) inspect the drain hose for kinks, and (7) if none of that works, the drain pump has likely failed — a pro job ($150–$300).

First, a safety note: standing water can hide broken glass. Wear rubber gloves and never reach in blindly — scoop water out with a cup first so you can see what you’re touching. If you work near the drain pump at the bottom of the tub, turn off power at the breaker first.

How a dishwasher drains (the 30-second version)

Understanding the drain path tells you where to look. At the end of the wash cycle, the drain pump pushes dirty water out through the filter, up through the drain hose, and into either the garbage disposal or the sink drain — usually passing through an air gap fitting on the sink rim first. A blockage at any point in that chain leaves standing water in the tub. Your job is to check each point in order, from easiest to hardest.

Step 1: Cancel and reset the cycle

Sometimes the dishwasher simply didn’t finish. A power blip, a bumped door latch, or an accidentally paused cycle can leave water in the bottom that the machine was about to pump out.

1. Press and hold the Cancel or Start/Reset button for 3 seconds (check your manual — on some models it’s a button combination).
2. The dishwasher should start a drain cycle that takes 1–2 minutes.
3. If the water drains, the “problem” was an interrupted cycle. Run a full cycle and confirm it completes.

If water remains, move on — the machine tried to drain and couldn’t.

Step 2: Clean the filter (the 2-minute fix)

A clogged filter is the single most common cause of standing water, and cleaning it takes two minutes.

1. Scoop out the standing water with a cup or large sponge so you can see the bottom of the tub.
2. Find the filter assembly — usually a cylindrical or flat mesh screen in the tub floor. It twists or lifts out (no tools needed on most models).
3. Rinse it under hot running water. Scrub off the greasy film with an old toothbrush and dish soap. For caked-on mineral deposits, soak it in white vinegar for 15 minutes.
4. While the filter is out, look down into the sump beneath it. Fish out food debris, labels, twist ties, or broken glass — wearing gloves.
5. Reinstall the filter and run a short cycle.

On many models, food particles that people assumed were “broken pump” problems turn out to be a filter that hadn’t been cleaned in a year. Make filter cleaning a monthly habit.

Step 3: Run the garbage disposal

If your dishwasher drains through the garbage disposal (very common in US kitchens), a full or jammed disposal blocks the dishwasher’s drain path.

1. Run cold water and turn the disposal on for 30 seconds. Listen for normal grinding — if it just hums, it’s jammed.
2. If jammed, turn it off, insert the Allen wrench that came with the disposal into the hex socket underneath, and work it back and forth to free the flywheel. Press the red reset button on the bottom.
3. Run the disposal until it clears, then run the dishwasher’s drain cycle again.

No disposal, or the dishwasher drains to a separate sink tailpiece? Skip to the next step.

Step 4: Check the dishwasher knockout plug (the classic gotcha)

This is the most common cause of a dishwasher that never drained once since installation. When a new garbage disposal is installed, its dishwasher inlet has a plastic knockout plug sealing it. If the installer forgot to knock it out, the dishwasher has been pumping against a sealed wall from day one — water goes nowhere.

1. Disconnect power to the disposal at the breaker (or unplug it).
2. Disconnect the dishwasher drain hose from the disposal inlet nipple.
3. Look inside the nipple with a flashlight. A solid plastic disc blocking it is the knockout plug.
4. Tap it out with a screwdriver and hammer, then retrieve the disc — don’t let it fall into the disposal chamber.
5. Reconnect the hose with its clamp and run a drain cycle.

If your dishwasher worked fine for months and then stopped draining, the knockout plug isn’t your problem — skip ahead. But if the dishwasher is new, newly installed, or a new disposal was just fitted, check this first.

Step 5: Check the air gap cap

Many kitchens have a small chrome or plastic cap on the sink rim or countertop behind the faucet — the air gap. It prevents dirty sink water from siphoning back into the dishwasher. Food debris clogs it regularly.

1. Pop the cap off — it usually twists or lifts.
2. Pull out the inner cap and clear the openings with a bottle brush or old toothbrush.
3. Rinse, reassemble, and run a drain cycle.

If the water was spurting out of the air gap onto the counter during the drain cycle, that’s a textbook air-gap clog — cleaning it almost always fixes it.

Step 6: Inspect the drain hose for kinks

The drain hose runs from the dishwasher to the disposal or sink drain, usually looped up high under the counter. Pull the dishwasher out slightly (or open the under-sink cabinet) and trace it: look for kinks, sharp bends, or crushing where it passes through the cabinet wall, and confirm a high loop rising near the underside of the countertop before descending — a hose lying flat drains poorly and lets dirty water flow back. Feel for a hard, clogged section; disconnect and flush it with a garden hose if you suspect a blockage.

Straighten any kinks, secure the high loop with a zip tie or bracket, and test again.

Step 7: The drain pump (call a pro)

If you’ve worked through steps 1–6 and the tub still holds water, the drain pump itself has likely failed — a worn impeller, a burned-out motor, or debris lodged where you can’t reach. You’ll sometimes hear it: a healthy pump makes a smooth humming-whir during the drain cycle; a failing one is silent, clicks, or grinds.

Turn off power at the breaker before touching the pump area. Replacing a drain pump means accessing the underside of the dishwasher, disconnecting hoses and wiring, and reinstalling the new pump without leaks. It’s a $150–$300 repair — at that price, with a dishwasher over 8–10 years old, compare against the cost of a new unit before proceeding.

What you’ll need

• Rubber gloves (non-negotiable with standing water — broken glass hides in it)
• A cup and sponge or old towels (to bail out water)
• An old toothbrush and dish soap (filter and air gap cleaning)
• White vinegar (mineral deposits on the filter)
• A flashlight
• Allen wrench (disposal jam) and screwdriver + hammer (knockout plug)
• Bucket (for catching water when disconnecting hoses)
• Zip ties or a hose bracket (securing the drain-hose high loop)

Cost estimates

Option	Typical cost
Reset the cycle	$0
Clean the filter	$0
Clear a jammed garbage disposal	$0
Knock out the disposal plug	$0
Clean the air gap	$0
Replace a kinked drain hose (DIY)	$10–$25
Drain pump replacement (pro)	$150–$300
New mid-range dishwasher	$400–$800

Safety warnings

• Broken glass hides in standing water. Always wear rubber gloves and bail the water out with a cup before reaching into the tub. Never reach in blindly.
• Turn off power at the breaker before touching the drain pump, disconnecting hoses underneath, or reaching into the sump beyond the filter. Water and live electrical components are a dangerous combination.
• Don’t use chemical drain cleaners in a dishwasher. They’re corrosive to the tub, racks, and pump seals, and residue can contaminate dishes. Mechanical cleaning is the way.
• If the dishwasher is leaking onto the floor, shut off the water supply valve under the sink and turn off the breaker before mopping up — electrical components sit under the tub.

Frequently asked questions

Is a little water in the bottom of the dishwasher normal? A small amount — up to about a cup — sitting in the sump around the filter is normal on many models; it keeps the pump seals from drying out. Water covering the tub floor, more than about an inch deep, is not normal.

Why is my dishwasher not draining after I installed a new garbage disposal? The knockout plug. New disposals ship with the dishwasher inlet sealed by a plastic plug that the installer must knock out. If it wasn’t removed, the dishwasher can’t drain at all. See Step 4 above — it’s a five-minute fix.

Can I run the dishwasher with standing water in it? Running another cycle with significant standing water won’t help and can make things worse — the pump may run dry or overheat. Bail the water out, work through the ladder above, then run a short cycle to test.

The dishwasher drains, but slowly and leaves dirty dishes. What’s wrong? A partially clogged filter — the pump pushes water through, but not enough for a proper wash. Clean the filter thoroughly (Step 2) and check the spray arms for clogged holes. If a sewer smell tags along, see Why Does My Dishwasher Smell Bad?.

Why is water coming up into the sink when the dishwasher drains? The shared drain line is restricted — usually a partial clog in the sink drain or a full garbage disposal. Run the disposal; if the sink itself drains slowly, clear the sink drain. The dishwasher is just revealing a drain problem that was already there.

How often should I clean the dishwasher filter? Monthly if you don’t pre-rinse dishes, every 2–3 months if you do. It takes two minutes and prevents most draining problems — the highest-value habit a dishwasher owner can have.

Prevention tips

• Scrape plates thoroughly before loading — the filter catches what you don’t scrape.
• Clean the filter monthly (two minutes, no tools).
• Run the garbage disposal before starting the dishwasher so the drain path is clear.
• Run hot water at the kitchen faucet for 30 seconds before starting the dishwasher — hot water dissolves grease instead of letting it congeal in the hose.
• Use the right amount of detergent; excess detergent leaves residue that clogs the filter faster.
• Check the drain hose high loop once a year, especially after any under-sink plumbing work.
• Never pour grease down the kitchen sink — it solidifies in the shared drain line and backs up into the dishwasher.

When to call a pro

• Steps 1–6 didn’t clear the standing water — the drain pump has likely failed ($150–$300 repair).
• The pump makes grinding, clicking, or no sound at all during the drain cycle.
• Water is leaking from under or around the dishwasher onto the floor.
• The dishwasher trips the breaker or smells like burning — an electrical fault, not a drain issue.
• The unit is over 8–10 years old and needs a pump — compare the $150–$300 repair against a new dishwasher.
• You find damaged wiring, a cracked tub, or corroded connections during inspection.