The answer, before the detail
A Black+Decker BDW dishwasher that leaves water behind is telling you the path out is blocked somewhere along its length. The path has four parts — sump, hose, air gap or disposer connection, and pump — and only the last needs a technician. This page works along the path in order, because that is the order that finds it fastest. On the BDW models the check that decides the order below is which build you have: a filter that twists out of the tub floor, or not.
What the owner actually sees
- Water standing in the tub at the end of the cycle — Note whether it is clean or dirty water — dirty means it never left.
- Water backing up into the sink when the machine drains — The shared drain line beyond the machine is restricted rather than the machine itself.
- Noise from the plumbing rather than the machine — Often the first sign, weeks before water is left behind.
- A smell from the tub between cycles — Water that is not leaving is water that is standing, and standing water in a warm tub smells.
- NEAR MISS — a small amount that never goes — Judge by what covers the tub floor, not by the recess.
Causes, ranked for the BDW build
- The filter and sump are blocked — On a grinder build it drops down the list, which is why establishing the build comes first. Lifting the filter out takes seconds and settles the question.
- The drain hose is kinked, blocked or has lost its high loop — It ranks high because it is common, invisible and free to fix. Look for the flat spot where something has been pressing on it.
- The check valve or the drain path inside the machine — It is ranked by pattern rather than by frequency. Dirty water means the drain never happened at all.
- The disposer knockout plug or the air gap is blocking the outlet — It also rises whenever a disposer has recently been replaced. An air gap on the worktop blocks with the same debris the filter catches.
- The drain pump is jammed or has failed — Last, because every cause above it is reachable without tools and this one is not. A hum with no drain, after the filter and hose are clear, is what is left.
The order that finds it fastest
- Clear the tub so you can see the filter area — Use a jug and a cloth, and watch for glass.
- Lift the filter and check underneath — A torch makes the difference between looking and seeing.
- Check the hose route, loop and any kinks — Second because it is the next part of the same path.
- Check the disposer connection or the air gap — An air gap comes apart by hand and blocks with the same debris as the filter.
Before you open anything
Safety
Power off at the breaker before any panel is removed — unplug it where the plug is reachable, because a capacitor can hold a charge after the power is off. Never wedge or defeat the door latch to watch a cycle run. Water on the floor and a mains-powered appliance are a bad pairing: dry the area before you work, and stop if the machine has been standing in water.
When to call a technician
Call when the filter, the hose route and the waste connection are all clear and the tub still holds water — that leaves the pump and the parts under the tub. Call sooner if you can hear the pump hum without moving water, or if there is glass in the sump: a fragment in the impeller is a common cause and a bad thing to fish for by hand.
Other faults covered for the BDW models
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
