Quick answer: Standing water in the bottom of a dishwasher is usually a clogged filter, a blocked air gap, a kinked drain hose, or, right after a new garbage disposal was installed, a knockout plug that was never removed. Clean the filter and check the disposal connection first. Typical repair: $100–$300. Expert Repair Company: $99 diagnostic, waived with repair, (279) 225-1050.
A dishwasher that finishes a cycle and leaves an inch of cloudy water in the bottom of the tub almost always has a clogged filter, a blocked air gap, or a kinked drain hose. The next most common cause, especially if you had a garbage disposal installed or swapped recently, is a knockout plug that was never removed inside the new disposal. A dead drain pump or a bad check valve come after that. Here is the order I work through the call, starting with what takes five minutes and no tools.
Why is my dishwasher not draining?
Most dishwashers that will not drain are physically blocked between the tub and the drain line, not electrically dead. The filter and sump catch food first, the air gap or high loop catch backflow second, and the drain hose or disposal connection catch it third. Only after all three are clear does a failed pump, stuck check valve, or control problem become likely.
Quick checks you can do safely
Turn off power at the breaker before you reach into the tub or under the sink, since the pump can restart mid-cycle.
- Pull the lower rack and lift out the filter. Twist it a quarter turn, rinse it under the faucet, and check the sump underneath for glass shards or produce stickers. A packed filter is the single most common cause.
- Check the air gap, the small chrome cap near the faucet. Twist it off and clear the two hose barbs underneath.
- Find the high loop. If a hose runs from the dishwasher to the disposal or under the sink, it should be strapped up high before it drops down, or it can siphon and never fully empty.
- If you just had a garbage disposal installed, suspect the knockout plug. New disposals ship with a plastic plug in the dishwasher inlet nipple. If the installer did not hammer it out, the dishwasher drains into a dead end.
- Run the disposal empty for a few seconds before running the dishwasher again, since a packed disposal blocks the shared drain line.
- Note any error code. Whirlpool, KitchenAid, and Maytag models often flash a code tied to the drain sensor.
What not to do: do not pour drain cleaner into the dishwasher tub, and do not pull the drain pump housing with the unit still plugged in.
Causes, from most to least common
1. Clogged filter or sump
Water sits over the filter screen, or the cycle sounds like it’s trying to drain but nothing moves. The part is the fine and coarse filter assembly at the bottom of the tub. DIY: nearly every dishwasher filter twists out by hand for cleaning, no tools required.
2. Garbage disposal knockout plug left in place
This shows up right after a new garbage disposal goes in. The dishwasher drains fine one day and backs up the next, because the plastic knockout plug inside the disposal’s dishwasher inlet was never removed. Technician job for most homeowners, since it means removing the drain hose from the disposal and reaching a recessed plug, and Expert Repair Company handles disposal work directly through our garbage disposal repair service.
3. Clogged air gap
Water backs up into the tub, or bubbles up around the air gap cap on the counter when the dishwasher runs. The part is the air gap fitting and its two short hoses. DIY: unscrew the cap and clear both barbs with a bottle brush or straightened wire.
4. Kinked drain hose or missing high loop
The dishwasher drains partway, or drains and slowly refills between cycles. The part is the corrugated drain hose to the disposal or air gap. DIY if it’s simply kinked; a missing high loop is a five-minute zip-tie fix once you know to look for it.
5. Failed drain pump
The dishwasher hums during the drain step and nothing moves, even with a clean filter and clear air gap. The part is the drain pump under the tub. Technician job, since reaching it usually means pulling the dishwasher out.
6. Stuck check valve
Water drains, then slowly siphons back into the tub between cycles. The part is the small rubber flapper check valve at the pump outlet. Technician job, since it sits inside the pump housing.
7. Interrupted cycle or control board fault
The cycle stops mid-drain, or the display shows a fault code that clears when you unplug and replug the unit. DIY: a full power cycle resolves a surprising number of these; if the code returns, it’s the control board or door latch switch, and a technician call.
8. Drain solenoid (older units)
On older dishwashers without a reversing drain pump, a separate solenoid opens a valve to route water out. If the tub fills and washes normally but never drains, and the unit is 15 years or older, the solenoid coil has likely failed. Technician job, and worth pricing against a new dishwasher at that age.
Brand notes and hard water
Bosch dishwashers route everything through a single micro-fine filter that must be removed and rinsed by hand rather than a self-cleaning macerating filter, so check it first on any Bosch complaint. Frigidaire and Whirlpool models more often show a drain fault code on the display before you even open the door. Across brands, a machine under 5 years old that suddenly won’t drain is almost always a clog, not a failed part. Sacramento-area hard water also leaves mineral scale inside the sump, check valve seat, and filter screen over time, narrowing the drain path gradually rather than blocking it all at once. A monthly dishwasher cleaner cycle slows this buildup, particularly in older Citrus Heights, Carmichael, and Orangevale homes. Bosch, Frigidaire and Whirlpool specifics are on the brands we repair page. The same drain-path logic applies to a washing machine that leaves the tub full; see washer won’t drain.
When to stop and call
Stop and call once the filter is clean, the air gap and disposal are clear, the hose has a proper high loop, and the tub is still holding water. At that point you’re looking at a pump, check valve, solenoid, or control board, each of which needs testing rather than guessing. Expert Repair Company provides dishwasher repair across the Sacramento area, and we carry the common drain pumps and check valves for Bosch, Whirlpool, Frigidaire, and KitchenAid on the van. Call (279) 225-1050, Monday through Friday, 8:00 AM to 5:00 PM. Same-day appointments are often available.
What the repair usually costs
Dishwasher repair typically runs $100 to $300, with an industry average around $200 and a published maximum near $650 for the most involved control board jobs. A filter or air gap clean-out costs nothing but your time. See the dishwasher and oven repair cost guide for the full breakdown and the 10-year rule.
Get the tub emptied and the dishwasher fixed
If your dishwasher keeps leaving standing water, don’t run it again until the tub is empty. Bail or sponge it out, check the filter and air gap above, and call Expert Repair Company for dishwasher repair. The $99 diagnostic fee is waived when you approve the repair, and $25 covers each additional appliance checked on the same visit.
