Check these, in this order
The order matters. It runs from the cause that is most common and costs nothing to the one that is rare and costs money.
Step 1. Bail the water out first
Scoop the standing water with a cup, then mop the last of it with a towel. Nothing else can be inspected while it is full, and the cheapest cause is usually visible only once the bottom is dry.
Step 2. Lift out the filter and clean it
The filter assembly sits in the floor of the tub, and on most machines it twists out anticlockwise. Separate the coarse mesh from the fine one, rinse both in hot water, and work a soft brush over the mesh. Grease film blocks flow just as effectively as visible debris, so judge it by feel rather than by eye.
Step 3. Check the knockout plug in the garbage disposal
This one catches a whole category of people at once. If the dishwasher was installed recently, or a disposal was replaced, and the machine has never drained properly since, the plug is almost certainly still in place. New disposals ship with a solid knockout in the dishwasher inlet that has to be punched out during installation, and missing it means the drain hose is connected to a sealed hole.
Step 4. Check the drain hose has a high loop
The hose must rise up under the countertop before dropping to the drain. Without that loop, water from the sink flows back into the machine and it never registers as empty. Missing high loops are one of the most common installation faults in American kitchens, and they cause exactly this symptom.
Step 5. Clean the air gap on the countertop
If there is a small chrome cylinder next to the faucet, that is the air gap. Twist the cap off, lift the cover and clear the chamber. It fills with grease and looks like a dead dishwasher when it blocks.
Step 6. Look under the filter at the pump
With the filter out, there is a cover over the drain pump. Take it off, unplug the machine, and turn the impeller with a finger. Glass fragments, fruit stones and bits of label jam it regularly. Check the cover is properly locked when you refit it: left loose, it causes a drain fault of its own.
Unplug the machine at the wall before reaching in, and use a torch. Broken glass in the sump is the usual reason people cut themselves on a dishwasher.
What a technician will look at next
Replace the drain pump
If the filter, hose, air gap and impeller are all clear, the pump has failed. It is a common repair at any age and needs the machine pulled out and tilted.
When to stop and call someone
Once the filter, the disposal connection, the hose and the impeller are all confirmed clear. Call sooner if the machine trips the breaker when the pump should run, or if water is appearing on the floor as well as in the tub.
What it costs
| Repair | Part only | Fitted by a technician |
|---|---|---|
| Cleaning the filter, air gap or hose | - | Free |
| Punching out the disposal plug | - | Free |
| Drain pump replacement | $20 to $100 | $100 to $400 |
| Plumber refitting the drain line | - | $100 to $250 |
If a code is showing too
Questions people ask
- There is water in the bottom after every cycle. Is that normal?
- A small amount, perhaps a cup, sitting in the sump is normal on many machines and keeps the seals from drying out. Water covering the filter or deep enough to reach the bottom rack is not.
- It smells. Do I need to do anything besides drain it?
- Clean the filter, then run an empty hot cycle with a dishwasher cleaner. The smell is bacteria in the film that built up while the water sat, and draining alone leaves it behind.
- Can I use drain cleaner in a dishwasher?
- No. Chemical drain cleaner attacks the pump seals and the plastic sump, and it will not reach the blockage anyway. The filter and the hose are the fix.