Standing water almost always means the drain path is blocked, not that the pump has died. Work the path in order: the filter or trap, then the hose and its high loop, then the air gap, then the pump itself. On a dishwasher installed alongside a new garbage disposal, check one thing first — if nobody knocked out the disposal's dishwasher plug during installation, the dishwasher has never had anywhere to drain to.
Read this first
- Unplug the machine before opening a pump filter or reaching into the sump. Broken glass and bra wires are the two most common things you will find, and both cut.
- Bail the tub before you open anything low on the cabinet — a front-load washer holds several gallons that will find your floor otherwise.
- Never reach into a garbage disposal chamber by hand, even to clear a dishwasher inlet. Power off at the breaker and use tongs or the hex wrench.
What it usually means
Drain systems are short and there are only a few places for them to block. A washer has a pump filter or a coin trap, a corrugated hose, and a standpipe. A dishwasher has a sump filter, a hose that must rise in a high loop or through an air gap, and the disposal or tailpiece it discharges into. Every one of those is reachable without special tools, which is why this is one of the most successful DIY repairs on the site.
A pump that runs but moves nothing sounds like a failure and usually is not — it is an obstruction the impeller cannot push past, most often a sock, a bra wire, a bone chip or a shard of glass. A pump that is silent when it should run is either a failed pump or, more often, a machine that never got the signal because the lid switch or the pressure sensor is unhappy. Listen at the start of the drain step; the sound tells you which.
What to check first
Bail the standing water out first
Towels, a cup and a bucket. Working on a full tub means the water goes on your floor the moment you open the filter, and on a washer it means the drain hose siphons back as soon as you move it.
Open the pump filter or coin trap
Front-load washers have an access flap at the bottom front; put a shallow tray and towels down before you unscrew it, because a full tub holds more than the tray will. Dishwashers have a twist-out cylinder filter in the sump. This is where the majority of blockages are found.
Check the disposal knockout plug
If your dishwasher has never drained since a disposal was installed, this is it. New disposals ship with a solid plug in the dishwasher inlet that must be knocked out during installation. It is a two-minute fix and an extremely common oversight.
Straighten the hose and confirm the high loop
Pull the machine out and look at the drain hose over its whole run. It must not be kinked, crushed behind the cabinet, or pushed more than a few inches into the standpipe. A dishwasher hose must rise to the underside of the counter or through an air gap before it drops, or the sink drains back into the machine.
Clear the air gap on the sink
That small chrome cylinder behind the faucet is a real part of the drain path. Twist the cover off, lift the cap, and clear the debris that collects inside it. A blocked air gap stops a dishwasher draining and often sprays water onto the counter as well.
Listen at the drain step
Start a drain cycle and put your ear near the pump. A hum or a grinding sound means the pump is powered and obstructed. Complete silence means it is not being told to run, which points at the lid switch, the pressure sensor or the control instead.
DIY, technician, or licensed trade?
This is about who is allowed to do the work, not how hard it is. The bottom row is not a difficulty rating — it is the legal and safety line, and it does not move for confidence or experience.
- Emptying a pump filter or coin trap and clearing the impeller of debris
- Knocking out a disposal's dishwasher plug
- Straightening or replacing a drain hose and fitting a correct high loop
- Cleaning the sink air gap and the disposal inlet
- Replacing a drain pump or its motor
- Replacing a pressure switch, water-level sensor or lid switch that is blocking the drain step
- Clearing a blockage in the sump or the dishwasher's internal drain path
- Anything past the trap — a blocked branch line or main drain is a plumber's job
- Re-plumbing a standpipe, tailpiece or air gap to meet local plumbing code
Likely parts and what they cost
Our estimates for a typical US job, not quotes. “Part only” is what the component costs bought online against a model number; “installed” adds a technician’s diagnostic and labor.
| Part | Part only | Installed | Notes |
|---|---|---|---|
| Drain pump | $40–$120 | $180–$400 | Replace only after confirming the impeller is clear and the hose is not blocked. |
| Drain hose | $15–$45 | $120–$250 | Cheap, and worth replacing rather than straightening a hose that has been crushed. |
| Pressure switch / water-level sensor | $25–$70 | $150–$320 | A blocked pressure hose reads as a full tub forever and stalls the cycle. |
| Sink air gap | $10–$30 | $100–$200 | Often just needs cleaning rather than replacing. |
| Plumber's drain clearing | n/a — licensed labor | $125–$350 | Only once the appliance side is proven clear. |
Prices are general estimates for typical US jobs, not quotes. What you actually pay depends on your appliance's brand and age, the part required, your region, and each shop's labour rate. Get the model number off the appliance before ordering — the same part varies in price across models.
Step-by-step guides for this symptom
4 guides cover this fault across 3 appliance types. Each one works through it in diagnostic order, with tools, parts and the point at which it stops being a DIY job.
- 45–90 minutesWasher
Washer Won't Drain — Work the Blockage Path in Order
Standing water in the drum? Follow the drain path in order — coin trap, tub-to-pump hose, pump impeller, drain hose, standpipe and pressure switch — before buying a pump.
- 30–90 minutesWasher
Washer Won't Spin — Diagnostic Guide
Clothes soaking wet at the end of the cycle? Diagnose a washer that will not spin: unbalanced loads, lid switches, drive belts, motor couplers and actuators.
- 20–60 minutesDishwasher
Dishwasher Not Draining — Clear the Standing Water
Water sitting in the bottom of your dishwasher? Clear the filter, sump, air gap, drain hose and disposal knockout plug with this step-by-step DIY guide.
- 45–90 minutesGarbage Disposal
Garbage Disposal Draining Slowly or Backing Up
Water rising in the sink when the disposal runs means a clog downstream, not a broken disposal. Clear the trap and branch line without chemical drain cleaner.