Troubleshooting guide
Dishwasher Not Draining? Causes and Fixes
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- ✓ 45-day parts & labor warranty
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Quick answer
Most dishwashers that won't drain have a clogged filter or sump, a blocked garbage-disposal connection, or a kinked drain hose. Clean the filter first, then run the disposal and check the hose under the sink. If the drain pump hums but no water moves, or makes no sound at all, the pump is jammed or has failed.
Standing water in the bottom of a dishwasher looks like a big problem. Usually it isn't. The water has one path out: through the filter, into the sump, through the drain pump, up the drain hose and into the disposal or sink drain. A blockage anywhere on that path stops the whole thing.
Work through the causes below in order. The first three cost nothing to check and fix a large share of the drain calls we see. One note before you start: a cup or so of water in the sump under the filter is normal on many models. An inch or more across the tub floor is not.
Causes, from most to least likely
1.Clogged filter or sump
Most dishwashers sold in the last 15 years use a manual-clean filter instead of a grinder. Food, labels, seeds and grease build up on the mesh until water can't get through to the drain pump. It's the single most common reason a dishwasher stops draining.
- Check it yourself
- Pull out the bottom rack. Twist the cylindrical filter (usually a quarter turn counterclockwise) and lift it out along with the flat mesh under it. Rinse both under the tap with a soft brush and dish soap. Clear any debris you can see in the sump opening, then reinstall until the filter locks.
- The fix · typical $120 – $190
- If the filter was the problem, the next cycle drains normally. If debris has packed into the sump below the filter, we clear it out and check that the drain path is open all the way to the sink.
2.Garbage disposal knockout plug or clogged disposal
Many dishwashers drain into the side of the garbage disposal. New disposals ship with a plastic knockout plug in that inlet. If whoever installed the disposal didn't punch it out, the dishwasher has nowhere to drain. We see this after rental turnovers and handyman disposal swaps. A disposal full of food waste can block the same inlet.
- Check it yourself
- If the disposal is new, this is the first suspect. Run the disposal with cold water for 20 seconds, then try a drain or cancel cycle. If the disposal was just installed, loosen the hose clamp on the dishwasher inlet, pull the hose off and look inside — a solid plastic wall means the knockout is still in place.
- The fix
- The knockout is tapped out with a screwdriver and hammer, and the loose plug has to be fished out of the disposal. If you're not comfortable doing that, a plumber or we can handle it in a few minutes.
3.Kinked, crushed or clogged drain hose
The drain hose runs from the back of the dishwasher, through the cabinet, to the sink drain. It gets kinked when the dishwasher is pushed back into its opening, or crushed by items stored under the sink. The hose can also clog with grease and food at the end where it meets the disposal.
- Check it yourself
- Look under the sink. Straighten any sharp bend in the hose and move cleaning supplies off it. The hose should rise to a high loop fastened up under the counter before it drops to the drain — that loop stops dirty sink water from flowing back into the dishwasher.
- The fix · typical $120 – $190
- A clogged or damaged drain hose is cleared or replaced. We also restore the high loop or air gap if it's missing, since backflow from the sink causes both drain and odor problems.
4.Blocked air gap
Some kitchens have a small chrome cap on the sink deck. That's an air gap, and some local codes require one. Dishwasher water passes through it on its way to the drain. When it clogs, water often spits out of the air gap onto the counter instead of draining.
- Check it yourself
- Pull or twist off the cap and the plastic cover under it. Clear out any food with a paper towel or a bottle brush. Run the dishwasher's drain cycle and watch whether water flows freely.
- The fix
- Cleaning usually solves it. If the hose from the air gap to the disposal is clogged, it gets cleared or replaced.
5.Jammed or failed drain pump
The drain pump is a small motor with an impeller that pushes water up the hose. A cherry pit, a piece of broken glass or a twist tie can jam the impeller. The motor can also simply wear out. A jammed pump often hums without moving water. A dead pump is silent when the dishwasher should be draining.
- Check it yourself
- With the dishwasher unplugged and the filter removed, look into the sump. On some models (Bosch is one) you can remove a small pump cover and see the impeller. If you can reach a visible object safely, remove it. Don't force anything apart.
- The fix · typical $170 – $290
- If the impeller is clear and the pump still won't run, the drain pump is replaced. It's a common part and often fixed on the first visit.
6.Stuck check valve
Most dishwashers have a one-way check valve at the pump outlet or in the drain hose connection. It keeps drained water from flowing back into the tub. If it sticks closed with debris, water can't leave; if it sticks open, dirty water flows back in after the cycle.
- Check it yourself
- This one is hard to see without pulling the dishwasher out. If the filter, disposal and hose are all clear and the pump runs, the check valve moves up the list.
- The fix · typical $170 – $290
- The valve is cleaned or replaced. On some models it's built into the drain pump housing, so the pump is replaced with it.
7.Control board not calling for a drain
The control board tells the pump when to run. A failed relay on the board, or a damaged wire to the pump, leaves a good pump sitting idle. Power surges during summer lightning storms are a common trigger for board failures in Pinellas.
- Check it yourself
- Write down any error code on the display and look it up in your manual. A board fault is the least likely cause, so rule out everything above first.
- The fix · typical $260 – $480
- We confirm the pump gets no voltage before replacing a board. Testing first means you don't pay for a board you didn't need.
When to call a technician
Call us if the filter is clean, the disposal and hose are clear, and water still sits in the tub — especially if the pump hums, grinds or stays silent. Call right away if water is leaking out of the dishwasher, not just sitting inside it. We'll find the blockage or the failed part, give you a written price before any work, and credit the $79 diagnostic to the repair.
45-day parts & labor warranty
Every repair carries a 45-day warranty on the parts we install and on our labor.
What the warranty covers →Common questions
Is some water in the bottom of a dishwasher normal?
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A small amount in the sump, under the filter, is normal on many models. It keeps the seals wet. Water covering the tub floor, or more than about an inch, means something is blocking the drain.
Can I use Drano or a chemical drain cleaner in my dishwasher?
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No. Chemical drain cleaners can damage the pump, seals and hoses, and they leave caustic water sitting in the tub. Clean the filter and check the disposal and hose instead.
Why did my dishwasher stop draining right after a new disposal was installed?
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The knockout plug in the disposal's dishwasher inlet was almost certainly left in. It's a common miss. Knocking it out and removing the loose plug from the disposal fixes it.
How often should I clean my dishwasher filter?
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Every two to four weeks for most households, more often if you don't scrape plates. If you notice gritty dishes or a smell, check it sooner.
How much does it cost to fix a dishwasher that won't drain?
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Clearing a clogged sump or drain path typically runs $120–$190, and a new drain pump $170–$290, including the $79 diagnostic credit. You'll get the exact price in writing before we start.
Related guides
Last reviewed 2026-10-07 by Mako Appliance Repair, Clearwater FL.
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