Dishwasher Not Draining? Common Causes and Safe Checks
Standing water usually comes down to the filter, the drain hose, the garbage disposal or the pump. Here is how to check them in order, and what to leave to a technician.
By Appliance Repair Temple · Published · Updated
Standing water: the quick answer
- A little water under the filter is normal. A pool covering the tub floor is not.
- Clean the filter first. It fixes a lot of drainage complaints.
- Run the garbage disposal, and on a new disposal make sure the knockout plug was removed.
- Check the drain hose under the sink for kinks and a proper high loop, and clear the air gap if you have one.
- If it hums at the end of the cycle and still will not drain, the drain pump likely needs a technician.
How much water is normal?
Many dishwashers keep a small amount of water in the sump, the low area under the filter, to keep seals from drying out. If you only see a little water down in that area, it may be normal.
Standing water across the floor of the tub, dirty water left after a cycle, or a sour smell are signs the dishwasher is not draining properly. If a cycle was interrupted by a power blip or someone opening the door, run a short cycle or a drain cycle once before troubleshooting.
Before you reach into the tub
Turn off the dishwasher’s power at the breaker or unplug it under the sink. Lay towels on the floor in front of it.
Bail out standing water with a cup and a small bowl, then soak up the rest with a sponge or towel. Watch for broken glass in the bottom of the tub and in the filter.
Dishwasher drain checks, easiest first
- Filter. Twist out the filter assembly under the lower spray arm and rinse it under the tap. Scrub mesh screens gently with a soft brush. Food, labels, seeds and glass collect here. Cleaning it about once a month is a good habit.
- Garbage disposal. If the dishwasher drains into a disposal, run the disposal for a few seconds to clear it. On a newly installed disposal, the knockout plug inside the dishwasher inlet may still be in place. Whirlpool suggests pushing a pencil into the inlet: if it goes in about three inches, the plug is gone.
- Sink drain. If the kitchen sink is slow or backs up, the clog is in the house plumbing, and the dishwasher cannot drain into it. Clear the sink drain first.
- The drain hose. Look under the sink for a hose that is kinked, crushed by stored items or sagging below the drain connection. Most installations call for a high loop, with the hose secured up under the counter so sink water cannot flow back into the dishwasher.
- Air gap. Some kitchens have a small cylinder on the sink deck next to the faucet. Pull or twist off the cap and clear any debris inside. Air gaps are required in some areas and optional in others.
Drain codes and sounds
Many dishwashers show a code when water does not leave in the expected time. Bosch, for example, uses codes such as E24 and E25 for drain problems, and other brands use their own codes or flashing light patterns. Check your manual or the manufacturer’s support site for your model.
Humming at the drain step with no water moving usually means the drain pump is jammed, often by glass or a seed, or its motor has failed. Silence at the drain step can point to the pump not getting power, a control or a wiring issue. A grinding or rattling sound can mean something is caught in the pump impeller.
When it is the pump
If the filter, disposal, sink drain, hose and air gap are all clear and the dishwasher still will not drain, the drain pump is the most likely cause. Some pumps can be cleared of debris; others need to be replaced. Either way, it involves removing panels and working near wiring and water, which is best left to a technician.
A failed drain pump is usually a reasonable repair. Replacement starts to make more sense mainly when an older dishwasher also has a rusted tub, broken racks or a failed control board.
Preventing drainage problems
- Scrape plates into the trash before loading. You do not need to rinse them, but large food scraps clog the filter.
- Clean the filter about once a month, more often if you rarely scrape plates.
- Run the garbage disposal before starting the dishwasher.
- In homes with hard water, use rinse aid and run a dishwasher cleaner every month or two to keep mineral scale out of the sump and drain path.
- Keep stored items under the sink from crushing the drain hose.
Questions
Can I use drain cleaner in my dishwasher?
No. Chemical drain cleaners can damage pump seals and plastic parts, and they are dangerous if they splash back. Clear the filter and check the hose instead.
Why does my dishwasher drain into the sink?
A clog in the sink drain or disposal lets water back up. A missing high loop in the drain hose can also let water flow the wrong way. Clear the sink drain first, then check the hose.
Why will my new dishwasher not drain?
On a new installation, a common cause is a garbage disposal knockout plug that was never removed, or a kinked drain hose behind the dishwasher. Check both before calling.
How often should I clean the dishwasher filter?
About once a month for most households, and more often if you do not scrape plates before loading.
Is a dishwasher that won’t drain worth repairing?
Most of the time. A drain pump is a common part. Replacement makes more sense mainly when an older dishwasher has several problems at once.
Sources
Dishwasher filters, sumps and drain codes differ by brand. Check your manual for your model, turn the power off at the breaker first, and watch for broken glass.