Published October 6, 2026 | uhfld
A dishwasher full of standing water looks like a broken machine, but most of the time it is a blockage you can clear yourself. Water leaves a dishwasher through a short, simple path: a filter at the bottom of the tub, a drain pump, a check valve, a hose that loops up under the counter, and then the garbage disposal or a sink drain. A blockage anywhere along that path leaves water sitting in the tub. Only one link in the chain, the pump, is an actual mechanical failure, and it is the last one to suspect, not the first.
A dishwasher that will not drain is usually caused by a clogged filter, a blocked garbage disposal or a knockout plug left in a new disposal, a kinked drain hose or clogged air gap, or a jammed or failed drain pump.
Clean the filter and run the disposal first; together they fix a large share of drain problems at no cost. If water still will not leave, and especially if the pump hums without draining, debris is jammed in the pump or the pump has failed.
This guide follows the drain path in order, from the inside of the tub to the sink, the same way a technician would check it. We repair dishwashers throughout Tampa, including the older bungalows of Seminole Heights, where kitchen remodels often pair a new dishwasher with decades-old drain plumbing, and Tampa’s hard water adds mineral scale to every part of the system.
Turn the dishwasher off at the breaker or unplug it before reaching into the tub or sump. Bail out the standing water with a cup and a sponge, and lay towels down. Feel carefully around the bottom of the tub: broken glass is one of the most common things found jammed in a drain pump.
Most dishwashers built in the last decade have a manual-clean filter, usually a cylinder that twists out of the floor of the tub with a flat mesh screen beneath it. Older designs ground food up and pumped it away; newer, quieter machines trap it in the filter instead, and the filter has to be cleaned by hand. Many owners do not know it is there.
Twist the cylinder out, lift out the flat screen, and rinse both under hot running water with a soft brush. Grease and food film can blind the mesh even when it looks clean, so scrub it. In Tampa, white mineral crust on the filter and spray arms is common; soaking the parts in white vinegar loosens it. Reinstall the filter fully locked in place, since a loose filter lets debris into the pump.
If your dishwasher drains into a garbage disposal, it can only drain as well as the disposal does. Run the disposal with cold water for 30 seconds, then try a drain cycle. A disposal packed with food blocks the dishwasher inlet.
If the disposal was installed recently and the dishwasher has never drained properly since, check for the knockout plug. New disposals come with a solid plastic plug sealing the dishwasher inlet, and it has to be knocked out with a screwdriver before the dishwasher hose is connected. It is easy to miss during installation, and the dishwasher cannot drain at all until it is removed.
The drain hose should rise in a loop as high as possible under the counter before it drops down to the disposal or drain. That high loop stops dirty sink water from siphoning back into the dishwasher. A hose that sags, or was pushed back too far during installation and kinked, either drains slowly or not at all.
Some kitchens have an air gap instead: a small chrome or plastic cap beside the faucet. If water spurts from the air gap when the dishwasher drains, it is clogged. Pull off the cap, unscrew the inner cover, and clear the debris with a brush or a bent wire.
If the filter, disposal and hose are clear and water still sits in the tub, the problem is the pump. Listen during a drain cycle. A hum with no water moving usually means the impeller is jammed, often by glass, a fruit pit or a bone. Silence can mean the pump motor has failed or is not getting power from the control.
On many models the pump impeller can be reached through the sump after removing the filter; turning it gently with a finger, with the power off, will tell you whether it spins freely. A one-way check valve between the pump and the hose can also stick shut. On Bosch dishwashers, error E24 generally points to a blocked drain hose or filter and E25 to a blocked drain pump or pump cover. Our Bosch repair page covers more Bosch codes.
For every other dishwasher problem, including leaks, no-heat and not-cleaning faults, see our dishwasher repair page.
A dishwasher that will not drain is usually blocked, not broken. The filter, the disposal and the drain hose account for most cases and cost nothing to check. The drain pump is the last link in the chain and the only one that typically needs a new part.
A small amount of water in the sump below the filter is normal on many models. Water standing above the filter level after a cycle means a drain blockage: most often a clogged filter, a blocked garbage disposal, a kinked drain hose, a clogged air gap or a jammed drain pump.
Turn the power off, twist out the cylindrical filter from the floor of the tub, lift out the flat mesh screen beneath it, and rinse both under hot water with a soft brush. Soak in white vinegar to remove mineral scale. Lock the filter fully back in place.
New disposals come with a plastic knockout plug sealing the dishwasher inlet. If it was not removed before the dishwasher hose was connected, the dishwasher cannot drain. Disconnect the hose and knock the plug out into the disposal, then remove it.
No. Chemical drain cleaners can damage dishwasher seals, the pump and plastic parts, and they leave a hazardous solution in a machine you use for dishes. Clear blockages mechanically instead.
E24 indicates a drain problem, usually a blocked filter, a kinked drain hose or a clogged connection at the disposal or sink drain. E25 points to the drain pump or pump cover being blocked.
That points to the pump, the check valve or a blockage under the counter. We carry common pumps and parts for most major brands.
Book a dishwasher repair Call (813) 722-0777
