Dishwasher Not Draining: the Drain Path, Step by Step

Of all the appliance faults we get called out to, this is the one most often fixed before we arrive — because the cause is a filter full of debris or a hose behind the machine, and both are reachable without tools. It is worth twenty minutes of your own time before booking anything.

Follow the Water: the Drain Path in Order

A dishwasher drains through a fixed sequence of components, and the fault is almost always at the earliest point where debris can collect. Checking them in this order saves you from taking anything apart unnecessarily.

That last row deserves attention because it is not an appliance fault at all. If the sink next to the dishwasher also drains slowly, the problem is the kitchen waste pipe and no amount of work on the dishwasher will fix it. Check the sink before you book anyone.

The Twenty-Minute Self-Check

• Switch it off at the wall or at the breaker before putting your hands in the machine
• Bail the water out with a jug and finish with a sponge or towels, so you can see the tub floor
• Twist out the filter, wash it under a hot tap with a brush, and hold it to the light — it should be visibly open
• Feel around the sump gently with your fingers, and expect to find glass. Anything hard that does not belong there comes out
• Look at the drain hose behind the machine: no kinks, not crushed against the wall, and rising to a high loop before it drops to the waste
• Check the air gap if there is one on the worktop — lift its cover and clear any debris inside
• If a disposal was fitted recently, check its dishwasher inlet plug was knocked out. It is moulded shut from the factory
• Run a short cycle empty and listen for the drain pump at the end: a hum with no water movement is a jammed impeller

A good share of these calls end at step three or four. If the machine drains properly after a filter clean, keep the habit — a quick rinse of the filter every month prevents the whole problem, along with the other maintenance in how to clean a dishwasher.

The High Loop, Explained

The single most common installation fault we find, and the cheapest to correct. The drain hose from a dishwasher must rise up high — ideally fastened under the worktop — before it drops down to the waste connection. That rise is called the high loop, and its job is to stop dirty water siphoning back out of the sink drain and into the machine.

Without it, two things happen. Water from the sink can flow back into the dishwasher, so you find standing water that the machine never put there. And the machine’s own waste water can partly return at the end of the cycle, which looks exactly like a drain pump failing. Some installations use a worktop air gap instead of a high loop, which does the same job through a vented fitting.

If you find the hose running flat along the floor from the dishwasher to the waste, that is a fault to fix regardless of what else is wrong — and it costs nothing but a cable tie. A hose that is also caked internally with grease needs replacing rather than cleaning, and that is a cheap part.

When It Is Not the Drain At All

Two cases look like a drain failure and are not.

• The cycle never finished. A door latch that does not register as closed, or a cycle interrupted by a power blip, leaves water in the tub because the machine never got to its drain step. The tell is a control panel that is not where it should be at the end of a programme
• A small amount of clean water is normal. Many machines keep a shallow film in the sump so the seals do not dry out. If you can cover it with a sponge, that is design, not a fault

The volume matters here. A cupful is normal on many machines. An inch or more across the tub floor is not, and that is the level at which food debris begins to sit in the water and the machine starts to smell. Standing water left for days also explains most complaints about a dishwasher that smells, since the debris in it is what turns sour rather than the machine itself.

Error Codes and What the Machine Is Telling You

Most machines made in the last decade will say something when they cannot drain, though every manufacturer words it differently. The categories are consistent even when the codes are not, so it is worth knowing which family your code belongs to before looking it up.

The leak-warning row is the one to take seriously. Machines with flood protection shut themselves down when a float or a moisture sensor trips, and repeatedly resetting one without finding out why it tripped is how a small leak becomes a floor repair. Look underneath before you run it again.

Stopping It Happening Again

Drain blockages are a maintenance fault more than a mechanical one, and the habits that prevent them are small. Rinse the filter under a hot tap once a month — thirty seconds, and it is the single highest-value thing you can do for a dishwasher. Scrape plates of bones, stones and skins rather than relying on the machine to grind them; modern filters are fine mesh precisely because modern machines use less water, and they clog faster than the older coarse ones did.

Run a hot cycle with a dishwasher cleaner or plain white vinegar every few months to shift the grease that coats the sump and the inside of the hose, especially in a hard-water area where scale and grease build together. Check the hose is still looped high whenever the machine is pulled out for any reason, since it is easy to leave it lying flat when pushing the machine back. And run the disposal with cold water before starting the dishwasher if they share a connection.

What the Repair Costs

Counted the same way across this whole site: a completed repair is a job billed above the $99 diagnostic.

Dishwashers are the cheapest appliance in our book to repair, and 87 percent of finished repairs under $400 is the reason. Drain faults specifically sit at the low end of that, because hoses, air gaps and blockages cost almost nothing to put right and a drain pump is a mid-priced part. Part-by-part figures are in the dishwasher repair cost database, and the replace-or-repair question by age is in how long dishwashers last.

What a Proper Diagnosis Checks

Standing water measured rather than eyeballed, since a film is normal and an inch is not; the filter and sump opened and cleared; the sump felt for glass and hardware; the drain impeller turned by hand; the drain pump tested for continuity and for a jam, which are different faults with different parts; the hose pulled out and checked end to end for kinks and internal build-up; the high loop or air gap confirmed present and correct; the disposal inlet plug confirmed removed; the sink waste tested independently to rule out a household blockage; the door latch and switch confirmed so the cycle actually reaches its drain step; and the control’s drain output observed on a live cycle.

Then the fault is named and the total quoted before anything is ordered. Dishwasher work in general is on the dishwasher repair page.

The hose itself, its routing, its sizing and how to check the loop in two minutes with a torch, are covered in the dishwasher drain hose.

If you are not sure the water is a fault at all, start there instead: water in the bottom of a dishwasher covers how much is normal, and the three tests that show whether it came from the machine or the sink.

If water is escaping the machine as well as failing to leave it, that is a separate fault with its own diagnosis: dishwasher leaking.

If everything upstream is clear, the pump itself is next — and its sound at the drain step tells you whether it is jammed or dead: the dishwasher drain pump.

On Whirlpool-built machines — Whirlpool, KitchenAid, Maytag, JennAir and Amana — the first question is whether yours has a cleanable filter or a food grinder: Whirlpool dishwasher not draining.

On a heavily insulated machine you cannot hear the pump at all, so feel for vibration and watch the air gap instead: KitchenAid dishwasher not draining.

Frequently Asked Questions