Bosch dishwasher not draining, water left in the bottom
Bought a Bosch dishwasher 18 months ago and there's a pool of dirty water sat in the bottom at the end of the cycle that won't drain away. What should I check first?
Solution Summary
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Bosch dishwasher leaving dirty water in the bottom due to likely drain blockage or pump issue
- The problem
- A Bosch dishwasher, about 18 months old, was leaving a pool of dirty water in the bottom at the end of the cycle and would not drain properly.
- Likely cause
- The accepted diagnosis was a drainage problem, most likely a blockage in the filters, sump, drain pump area, drain hose or sink waste connection. If those were clear, a failed drain pump or wiring/control fault was suggested as possible.
- What fixed it
- Recommended first checks were to isolate the appliance from the mains, clean the filter assembly, inspect the sump for debris, check the drain pump area and impeller for obstructions, inspect the drain hose for kinks or blockages, and check the sink trap/waste spigot connection including whether a blanking plug had been removed. If the pump hummed during a drain but little water exited, a blockage or restricted hose was considered likely. If the pump was silent, pump or supply faults were suggested. No specific completed repair was confirmed in the thread.
- Checks to try
- Cleaned/checked filter assembly
- Inspected sump area for food debris, glass, labels or grease build-up
- Checked drain pump cover area for debris
- Checked whether pump impeller turned freely
- Inspected drain hose for kinks, crushing or blockages
- Checked connection to sink trap or waste spigot
- Confirmed whether any blanking plug in a new trap spigot had been removed
- Listened during a cancel/drain programme for pump noise
Safety: Isolate the dishwasher from the mains before checking internal areas. Further diagnosis should be carried out by a suitably qualified appliance engineer.
1 Answer
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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This answer was generated automatically by the WhitegoodsHelp AI Assistant. It is not provided by an engineer or any other qualified person, may be inaccurate or incomplete, and is not professional or technical advice. Do not rely on it. Always use your own judgement and consult a qualified engineer before carrying out any electrical, gas or water work. Use is entirely at your own risk. See our full Terms of Use.
SAFETY FIRST: READ BEFORE ACTING ON THIS GUIDANCE
Never work on a live appliance
Always unplug it at the mains before going near it with any tools.
Never attempt gas work
By law, gas appliances must only be worked on by a Gas Safe registered engineer. If your fault involves gas, stop and call a professional. Do not attempt it yourself.
Watch for sharp edges
Outer panels are smooth, but internal parts have sharp machined edges. Wear protective gloves and arm sleeves.
Water appliances can leak
Turn off the water supply before disconnecting any hoses.
Know your limits
If you are not confident testing or working inside the appliance, stop and call a professional.
AI guidance, not guaranteed
This response is generated automatically by the WhitegoodsHelp AI Assistant. It is not professional or technical advice, may be incomplete or wrong, and must not be relied upon. Always use your own judgement and consult a qualified engineer before any electrical, gas or water work.
This is general information only and is not professional advice. The WhitegoodsHelp AI Assistant is not an engineer and is not qualified. See our full Terms of Use.
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