The short answer
Most dishwasher leaks are not a failed component: they are a door that no longer seals square, or foam that has climbed out of the tub. Where the water shows itself tells you which one you have. Water at the door front points at the seal, the latch or the stance; water under the middle of the machine points at the sump, a hose clamp or a fitting. On a Smeg dishwasher the cause that ranks first is door gasket hardened, displaced or fouled.
What you observe
- Water only while the machine is running, never when it is idle — Points at the wash circuit rather than at the supply plumbing.
- A swollen or stained cabinet plinth and a soft floor patch — The leak has been running longer than it has been visible.
- NEAR MISS — water stands inside the tub instead of on the floor — That is a drainage fault, and it has its own page.
Causes, most likely first on a Smeg dishwasher
- Door gasket hardened, displaced or fouled — The seal takes a set with age and heat, or a crumb sits on the sealing face, and hot water finds the gap along the bottom corner first. It ranks first on a Smeg dishwasher because the European control aborts rather than pushing through a fault, so the sensor and lock causes surface ahead of the mechanical ones.
- Cabinet out of level, so the door lands untrue — A machine that is tipped or twisted in its opening puts the load on one side of the door seal and lets water run forward instead of back to the sump. Second on this platform: the stance changes whenever the machine is fitted, moved or re-plumbed, and nothing else in the path does.
- Fill valve overfilling, or a stuck float — The tub fills past its normal level, the water reaches the door seal from the inside, and it leaks at the bottom of the door on every cycle. Last, and the reason to work down the list rather than guess: an overfill leaks in exactly the same place a tired gasket does, which is why the level is worth confirming.
Check in this order, and why
- Run a sheet of paper round the closed door and look for the slack corner — It separates the seal from the stance in under a minute.
- Put a level on the door edge, side to side and front to back — The stance is behind more door leaks than the seal is.
- Open the door mid-wash and look at where the water sits relative to the heater — A level above the element is an overfill, not a seal.
What an owner can safely check
- Wipe the gasket and the frame it lands on, then check the seal grips the paper all the way round — A gasket that has flattened at one corner is the answer.
Tools: cloth, paperAbout 10 min
- Adjust the feet until the machine sits level and the door closes without being pulled — Check the fixing to the worktop has not twisted the frame.
Tools: spirit level, spannerAbout 20 min
- Run a rinse-only cycle with no detergent and watch the door line — If the machine stays dry, the detergent was the fault.
About 25 min
- STOP at the point where the next check means live terminals or a panel removed — Everything past that line is a technician's work, however likely the cause above it looks.
Before you open anything
Safety
Unplug the machine or switch off its breaker before removing any panel — a capacitor can hold a charge after the power is off. Dry the floor before you work beside a powered appliance, and shut the supply valve before touching any plumbed joint.
When to call a technician
Call when the door seal, the stance and the detergent are all ruled out and water is still arriving, or the moment the water is coming from under the centre of the machine rather than the door. On a European-controlled machine, ask what the control was reporting when it stopped — it usually records why it aborted, and that shortens the visit.
Nearest pages of this class
What this page does not cover
What this page covers is the dishwasher class as Smeg builds it, not an individual family or model line. If a page exists for your particular family or model, it is linked above and it is the better answer — go there first when your model is named. Left out on purpose: part numbers, connector colours, disassembly order and torque values, because every one of those varies by family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
