· Marian Appliance Repair
A little water in the bottom of a dishwasher after a cycle is normal. When a dishwasher won't drain or isn't emptying, something between the filter and your sink drain is often blocked: a clogged filter, a backed-up sink or garbage disposal, a clogged air gap or a kinked or clogged drain hose. Check them in that order, from the jobs that need no tools to the ones that need a technician.
This guide is written for homes in San Jose and across Santa Clara and Santa Cruz counties. If water is spilling out of the small cap next to your faucet while the dishwasher drains, read our guide to the dishwasher air gap as well.
- Bosch says up to about two cups of water left in the bottom after a cycle is normal for its dishwashers.
- Turn the power off and bail the water out before you start, and feel carefully: debris in the sump can be sharp.
- Check in order: filter, pump cover, sink and disposal, air gap, drain hose. Then stop and call.
- Never pour drain cleaner into a dishwasher. Sub-Zero warns it can cause permanent damage.
- Several slow drains in the house mean a plumber. If only the dishwasher holds water, look at it and its own drain connection.
Is the water in the bottom normal?
Some water is meant to be there. Bosch says it is normal to see a small amount, usually up to two cups, in the bottom of its dishwashers after a cycle, and that more water than usual can mean a clogged or dirty filter.
Before you look for a fault, make sure the cycle actually finished. A dishwasher left paused can stop with water still in the tub.
Water covering the filter, water that smells, or dishes sitting in dirty water after a full cycle means the dishwasher is not draining.
First, get the water out safely
Turn the dishwasher off at the breaker or unplug it before you put your hands in the tub. Lay towels on the floor in front of the door, scoop the water out with a cup, and finish with a sponge.
Go slowly around the filter and the sump below it. Bosch warns that some debris in the pump area may be sharp, so wear gloves if you have them.
Two things not to do. Do not pour drain cleaner into the dishwasher or its drain: Sub-Zero, Wolf and Cove tell owners never to use Drano, CLR or any other chemical cleaner to unclog a dishwasher drain, because chemicals can cause permanent damage. And do not keep running cycles in the hope that it clears.
What to check, in the order a technician does
1. Clean the filter
Lift out the filter at the bottom of the tub, under the lower spray arm, and rinse it under the tap. Labels and bits of plastic block it as well as food does.
2. Check the pump cover
With the filter out, look for the small cover over the drain pump. On Bosch dishwashers a loose or missing cover is enough to stop draining, and the cover pries off with a spoon so you can sponge out what is under it. Other brands differ, so check the manual before prying anything.
3. Run the sink and the disposal
Run water in the kitchen sink. If it drains slowly or backs up, the clog is in the sink drain or the garbage disposal, not the dishwasher. Run the disposal to clear what is sitting in it, then try draining the dishwasher again.
4. Ask whether the disposal is new
If the trouble started right after a new garbage disposal went in, suspect the knockout plug. It is a small piece inside the disposal's dishwasher inlet that must be removed before the drain hose is connected, and Bosch notes a new installation may have left it in place.
5. Look at the air gap
The small chrome or plastic cap on the sink next to the faucet is the air gap. Water spilling out of it while the dishwasher drains means the path below it is blocked, and food can clog the air gap itself. Pull the cap off and clear it with a bottle brush.
6. Check and flush the drain hose
Under the sink, follow the drain hose back toward the dishwasher and straighten any kink. If it still will not drain, the hose may be clogged inside. With the power and water off, it can be detached at both ends, flushed through with water and refitted.
7. Not draining but no blockage? Stop here
If the filter, sink, disposal, air gap and hose are all clear and the water is still there, the fault is inside the dishwasher: the drain pump, a valve or the controls. A hum or grinding with no water moving, or no pump sound at all, is the moment to call.
Is it the dishwasher or the house drain?
One question saves a wasted visit. If the kitchen sink, the bathroom sinks and the tub are all slow, the blockage is in your home's drain line, and that is a plumber's job. If everything else drains normally and only the dishwasher holds water, the problem is the dishwasher or its own connection under the sink.
Why drains back up after big dinners
Holiday cooking is hard on kitchen drains. Roto-Rooter said in 2023 that the day after Thanksgiving is its busiest of the year, with about 50% more calls than an average Friday, and named clogged kitchen sinks and garbage disposals among the main culprits. The dishwasher drains through that same sink drain or disposal.
Wipe grease out of roasting pans with a paper towel and keep cooking oil out of the drain. In Santa Clara County, cooled cooking oil in a jar with a lid can go to the county's Household Hazardous Waste program by free appointment.
Bosch, Whirlpool, GE and other brands
Many dishwashers report a drain problem as an error code. On Bosch models, E24 means the dishwasher is not draining properly, which Bosch ties to a blocked drain filter, and E25 means the drain pump is blocked or its cover is loose or missing. Treat any code as a place to look, not a part to buy, and check your manual for what your model's code means.
We repair Bosch, Miele, Thermador, Whirlpool, GE and other dishwashers, built-in and standard.
When is it a job for a technician?
Call a technician when the filter, sink, disposal, air gap and hose are clear and the water is still there; when you hear no pump running during the drain, or a hum or grinding instead; or when the problem started after work on the plumbing.
We repair dishwashers at your home in San Jose and across Santa Clara and Santa Cruz counties, using original spare parts. Diagnosis and repair are carried out on site, and if a repair is not worth it on an older machine, we will tell you.
Common questions
How much water should be left in the bottom of a dishwasher?
A small amount is normal. Bosch puts it at up to about two cups after a cycle for its dishwashers. If water covers the filter or the dishes are sitting in it, the dishwasher is not draining.
Can I use Drano to unclog a dishwasher?
No. Sub-Zero, Wolf and Cove tell owners never to use Drano, CLR or any other chemical cleaner to unclog a dishwasher drain, because the chemicals can cause permanent damage. Clean the filter and clear the sink side by hand instead.
Why won't my dishwasher drain after a new garbage disposal was installed?
Most likely the knockout plug was never removed. It is a small piece inside the disposal's dishwasher inlet that must come out before the drain hose is connected. Removing it means working at the disposal with its power off; if you would rather not, call us or a plumber.
How do I clean a dishwasher drain hose?
Turn off the power and the water, detach the hose at both ends with a towel underneath, and flush it through with water, using a brush on the fittings. Refit it and run a drain to check.
Is there a reset button on a dishwasher?
Button sequences vary by brand, so check your manual. A reset will not clear a clog, though: if water is still sitting in the tub, work through the checks above.
Dishwasher still holding water? Call us
We repair dishwashers at your home in San Jose and across Santa Clara and Santa Cruz counties, with same-day service and a 3-month warranty on labor and parts.
