The short answer
On the COSDWI family the usual reason a Cosmo dishwasher is leaking water is door gasket not seating, and that is where the order below departs from the brand-generic article one level up: on the manual-filter build it outranks overfill from an inlet valve that does not close. The check that confirms which build you have is simple — a removable filter cylinder in the sump means the seal that matters most sits under it, where the pump meets the tub. The gasket, the loading, the detergent and the levelling are owner work; the sump seal and the inlet valve are not.
What you observe on these models
- Water at the front, under the door — The classic seal or tilt presentation, and both are checkable in minutes.
- Water under the centre of the machine — Away from the door, which moves the question to the sump.
- A puddle under the sink rather than the machine — The drain joint, which sees water only at the drain step.
- Water that appears with the machine switched off — Only the pressurised supply side can do that.
- Foam visible through the door near the end — Chemistry rather than mechanics, and instantly reversible.
- NEAR MISS — water standing inside the tub instead — That is a drainage fault and the drainage page is the right one.
Causes, most likely first on the COSDWI family
- Door gasket not seating — Ranked first here: the gasket runs the whole way round the door and only has to fail at one point. Debris on the seal, a hardened corner or a stray item caught at the edge all let water out at the bottom of the door.
- Overfill from an inlet valve that does not close — Second: a valve that weeps when the machine is idle slowly raises the level until the tub overflows at the door, usually overnight when nobody is watching.
- Inlet hose fitting at the valve or the tap — Third: the supply side is under mains pressure all the time, not just during the cycle, so a weeping fitting delivers water whether the machine runs or not.
- Drain hose joint under the sink — Fourth: it is worth ranking because the puddle appears under the sink rather than under the machine, which sends people looking in the wrong place.
- Sump or wash-pump seal — Fifth: it sits low because everything above it is more common, and because this is the first cause on the list that is a real repair.
- Spray deflected past the door by the load — Sixth: it produces an intermittent leak that follows the load rather than the machine, which is exactly what owners describe as random.
Check in this order, and why
- Run a finger round the gasket for debris or a hardened corner — Visible, wipeable, and the most common finding on a front leak.
- Note whether water appears with the machine switched off — Only a weeping inlet valve fills a tub that is not running.
- Dry behind the machine and look again after an idle hour — The supply side is pressurised all the time, so an idle leak points there.
Before you open anything
Safety
Power off at the spur, water off at the valve, then open anything. Those two come first because the wiring and the plumbing in this cabinet run alongside each other. Leave the door latch alone: defeating it lets a hot cycle run with the door open. Bail the water out before you tip the machine forward, and treat anything in the sump as sharp until you have seen it. Get a second person before you pull the cabinet out or tilt it.
Models in the COSDWI family
Reference| Model number | Family key |
|---|---|
| COS-DWI240TT*** | cosmo:dishwasher:cosdwi |
| COS-DWI24TTG | cosmo:dishwasher:cosdwi |
| COS-DWI24TTR | cosmo:dishwasher:cosdwi |
When to call a technician
Once the free checks are clean the remaining causes are the sump seal and the inlet valve, both of which need the machine drawn out and the power isolated. Shut the supply off first, then call.
