The short answer
Most dishwasher leaks are the door seal or a connection behind the machine, not the tub. Dry everything, put paper down, and run one cycle watching - the stage the water appears at is most of the diagnosis.
What you actually see and hear
- Water at the front along the floor during the wash — Door seal or door alignment, by far the commonest.
- Water appearing only after the cycle, at the back — A drain connection or the hose behind the machine.
- A damp plinth with no visible source — A slow supply weep, which can run for weeks before it shows.
- Suds on the floor — Wrong detergent or a rinse-aid overdose rather than a fault.
- NEAR MISS - water when you open the door at the end — Condensation running off the door. Normal on a hot cycle.
Causes, most likely first on this machine
- Door seal, door alignment or a trapped item — First on a compact machine. The seal is a single continuous strip, and a spatula handle or a stray plate edge holding the door a fraction open puts water on the floor every time.
- Drain hose connection at the waste — Second. It is clamped on a spigot behind the machine, it is disturbed whenever anything is done under the sink, and it leaks only while the pump runs.
- Supply hose fitting or the isolating valve — Third. It weeps under mains pressure all day rather than during the cycle, which is why it soaks the plinth unnoticed.
- Detergent overdose or the wrong product — Fourth, and always worth ruling out before parts are bought: suds push water past a seal that is otherwise sound.
- Sump gasket, spray arm feed or tub seam — Last. Real, but the least likely and the only one that needs the machine pulled out and opened.
Check in this order, and why
- Dry the floor and lay kitchen paper front and back — Paper shows the first drop and where it came from, which nothing else does.
- Run one cycle and note when water appears — Fill, wash and drain each implicate different causes.
- Run a finger round the whole door seal — Looking for grit, tears and a fold that has stopped sitting flat.
- Pull the machine forward and feel the connections with a tissue — A tissue finds a weep that a hand will miss.
What an owner can safely check
- Dry everywhere and put paper down front and back — Attribution first - without it you will be guessing at the wrong end of the machine.
Tools: towels, kitchen paperAbout 15 min
- Clean the door seal and the door edge it closes against — Grit in the seal is the single most common leak on a compact machine.
Tools: clothAbout 10 min
- Check nothing in the racks is holding the door fractionally open — A tall handle in the top rack is enough.
About 5 min
- Turn the water off, then feel the supply and drain connections — Any dampness at a fitting is a fault however small it looks.
Tools: tissue, towelAbout 20 min
- Use the correct dishwasher detergent at the recommended dose for one cycle — If the leak stops, it was suds and no part was ever faulty.
About 90 min
- STOP HERE before opening the sump or resealing the tub — That needs the machine out of the cabinet and the supply isolated.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel - a capacitor can hold a charge after the power is off. A dishwasher sits in a wet cabinet with a live supply behind it, so switch off at the breaker before pulling it out, and turn the water off at the isolating valve under the sink before any hose is touched. Do not lean on an open door to reach the back of the cabinet.
When to call a technician
Call when the door seal is clean and intact, the connections are dry and water still reaches the floor - that points at the sump, the tub or a spray feed inside, and it means pulling the machine out. Call urgently if water has been reaching a plinth or a floor void for any length of time, because the damage to the cabinet and floor usually outruns the damage to the appliance. Turn the isolating valve off in the meantime; a dishwasher that leaks under mains pressure does not wait for an appointment.
Nearest pages of this class
What this page does not cover
This page is written for the slimline built-in dishwasher class, not for one family or model line. Where a brand- or model-specific page exists for your unit it is the more specific answer and it is linked above, so go there first if your machine is named. What is deliberately not here: spray arm and pump part numbers, hose specifications, door spring tensions and control diagnostics, all of which differ by family and belong on the page for that family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
