A dishwasher that leaves an inch of cloudy water in the bottom of the tub is one of the most common calls we get, and the good news is it's rarely the control board. In most cases the problem is mechanical — something is blocking the water's path out of the machine — and it's usually one of a small handful of parts.
Start with the filter
Most dishwashers built in the last decade use a manual filter at the bottom of the tub rather than a garbage-disposal-style grinder. Food debris, glass shards, and produce stickers collect there over time, and once it's clogged enough, water can't drain fast enough to clear the tub between cycles. Pull the filter (it typically twists out by hand) and check it before assuming anything else is wrong.
Drain hose and air gap blockages
If the filter is clear, the next place to check is the drain hose and, if your installation has one, the air gap on the sink or countertop. A kinked hose behind the dishwasher or a clogged air gap will produce the same symptom — standing water — even though the pump itself is working fine.
Drain pump failure
If the filter and hose are both clear, the drain pump itself may have failed or be jammed by a small object — a piece of glass or a bottle cap is a common culprit. A pump that hums but doesn't move water, or doesn't run at all, needs to be tested directly rather than guessed at.
Check valve and float switch issues
Some dishwashers use a check valve to prevent water from siphoning back in after it drains. If that valve sticks, water can re-enter the tub right after the pump clears it, which looks identical to a drain that never worked in the first place. A stuck float switch can produce similar symptoms by preventing the control board from ever starting the drain cycle.
- Check and clean the lower filter first — it's the single most common cause.
- Run the garbage disposal (if the dishwasher drains through it) to clear any disposal-side blockage.
- Don't run another wash cycle on top of standing water — it can overflow onto the floor.
- Note whether the pump makes any sound at all during the drain portion of the cycle before your appointment.
If you've checked the filter and the water is still standing after a full cycle, it's worth having a technician trace the water path rather than replacing parts by trial and error — that's usually the faster and cheaper path to a fix.