Bosch dishwasher not draining, water left in the bottom

If there’s dirty water left in the base at the end of the programme, the most common causes are a blockage, a kinked drain hose, or a drain pump issue rather than anything major.

Before checking anything internal, isolate the dishwasher from the mains.

1. Check the filters and sump Remove the lower basket, take out the filter assembly and clean it thoroughly. Look down into the sump area for food debris, glass, labels or grease build-up. A partial blockage here is very common.

2. Check the drain pump area On many Bosch dishwashers you can access the pump cover near the filter. Remove any debris carefully and see whether the pump impeller turns freely. If it is jammed by broken glass or feels stiff, that can stop draining.

3. Check the drain hose Pull the machine forward if needed and inspect the drain hose for kinks, crushing or blockages. Also check where it connects to the sink trap or waste spigot. If it goes into a spigot under the sink, make sure that connection is not blocked with sludge.

4. Listen during drain Run a cancel/drain programme. If you can hear the pump humming but little or no water comes out, there is likely a blockage or restricted hose. If it is completely silent, the pump or its supply may be at fault.

5. Check the sink waste connection If the dishwasher was connected to a new trap, confirm the blanking plug was removed from the spigot.

If all of the above are clear, the drain pump itself may have failed or there may be a wiring/control fault. For mains-related testing, or if you are unsure, it’s best to use a qualified appliance engineer.

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