Dishwasher Not Draining? Common Causes and What You Can Check
A dishwasher that leaves standing water after a cycle usually has a clogged filter, a kinked hose, a disposer plug or a failing drain pump. Here is what to check and when to call a technician.
Standing water at the bottom of the tub after a cycle means the water is not leaving the machine. Sometimes it is a simple blockage you can clear in a few minutes. Other times a part has worn out and needs a technician.
Most drain problems come down to a handful of things: the filter, the drain hose, the garbage disposer connection, the air gap if you have one, and the drain pump itself. Working through them in that order saves time and avoids a service call you did not need.
Turn the dishwasher off at the breaker or unplug it before reaching into the tub or pulling the unit forward. Water and power do not mix, and the water standing inside may be dirty and contain broken glass or sharp food scraps. Wear gloves, use a towel and a shallow container to remove water, and never put your hands near anything inside the cabinet. The machine is heavy, so do not pull it out alone.
What you can safely check first
- Run a short cycle or the cancel and drain option once. Some machines hold water after an interrupted cycle and drain when reset.
- Look for debris at the bottom of the tub: bits of glass, labels, olive pits, toothpicks. Remove what you can see by hand with the power off.
- Take out the lower rack and clean the filter. Most twist or lift out. Rinse it under the tap and brush off any grease or grit, then refit it firmly.
- Check the drain hose behind or under the machine for kinks or crushing, if you can see it without moving heavy cabinets. Straighten it gently.
- Run the kitchen sink disposer empty with water running, in case the shared drain is partly blocked. If the sink is also slow, the problem is the household drain line, not the dishwasher.
- If you have an air gap on the counter or sink top, lift the cap and clear any gunk you can reach.
Common causes
A clogged filter or sump
The filter catches food before it reaches the drain pump. When it clogs, water drains slowly or not at all, and the dishes often come out gritty. This is one of the most common causes and the easiest to rule out yourself with a clean.
A kinked or blocked drain hose
The hose carries water from the pump to the sink drain or disposer. A bend from a tight installation, a crushed section or a build-up of grease inside can stop the flow. A technician can check the full run of the hose, including parts you cannot reach.
The disposer knockout plug on a new install
When a dishwasher is connected to a garbage disposer, the disposer inlet has a thin knockout plug that must be removed first. If it was left in during installation, water has nowhere to go. This is a classic cause when a dishwasher never drained properly from day one, or after a new disposer was fitted.
A clogged air gap or high loop problem
An air gap is a small fitting on the counter that prevents dirty sink water from flowing back. It can fill with debris and block the drain line. Without an air gap, the hose should rise in a high loop under the counter. If it sits too low, drainage can be poor.
A failed drain pump
The drain pump pushes water out of the tub. A pump can jam on debris, wear out or lose power. If you hear a humming sound without water moving, or no sound at all, the pump or its wiring is a likely suspect. A technician tests it and replaces it if needed.
When to call a technician
Call a technician if the filter is clean, the hose looks fine and the water still will not leave. The same goes for a humming or silent pump, repeated tripped breakers, or water leaking onto the floor.
Also call if the dishwasher was recently installed and has never drained. A technician can check the disposer connection and the hose route properly, without you taking apart plumbing.
Still not working? Book a dishwasher repair and tell us the model number and what you have checked.
Frequently asked questions
Is it safe to run the dishwasher with standing water in it?
It is better not to. Standing water can smell and may overflow into the kitchen if the cycle fills it further. Remove what you can with a cup, check the filter and call for repair if it persists.
Why does my dishwasher drain into the sink?
Some water backing up from the sink side usually points to a blocked disposer, drain line or air gap. If both the sink and the dishwasher are slow, the household drain needs attention first.
Can a new garbage disposer cause a dishwasher drain problem?
Yes. The disposer inlet for the dishwasher hose is sealed with a knockout plug at the factory. If it was not removed during installation, the dishwasher cannot drain into it.
Should I replace the drain pump myself?
We do not recommend it. It involves power, water and removing the machine from its space. A technician can confirm the pump is the real fault before any part is replaced.
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