The short answer
On the COSDWH family the usual reason a Cosmo dishwasher is leaking water is inlet hose fitting at the valve or the tap, and that is where the order below departs from the brand-generic article one level up: on the compact or countertop build it outranks drain hose joint under the sink. A narrow cabinet or a portable unit with a tap coupling puts every joint within reach and in view. 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.
- 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.
- Water under the centre of the machine — Away from the door, which moves the question to the sump.
- 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 COSDWH family
- Inlet hose fitting at the valve or the tap — Ranked first here: it ranks first on a portable or compact machine because the tap coupling is made and broken by hand every time the machine is used.
- Drain hose joint under the sink — Second: the joint at the waste or the disposer sees water only at the drain step, which produces a leak that appears once per cycle and then stops.
- Spray deflected past the door by the load — Third: a tall tray on the front edge of the lower basket turns the spray straight at the door seal instead of at the dishes. The seal is not designed to take a jet.
- Overfill from an inlet valve that does not close — Fourth: it is on the list because the puddle appears with the machine switched off.
- Machine tilted forward — Fifth: these machines are meant to sit level or very slightly back. Tipped forward, the tub carries water to the door on every wash and the seal is asked to hold back a standing level.
- Over-sudsing pushing water past the seal — Sixth: it belongs on the list because it is instantly reversible and because the foam is visible through the door in the last minutes of a cycle.
Check in this order, and why
- 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.
- Watch the joint under the sink during the drain step — A once-per-cycle leak in a place people do not look.
- Reload with nothing tall on the front edge — A tray aiming the spray at the door produces a leak that follows the load.
Before you open anything
Safety
Switch the machine off at its spur or unplug it, and shut the isolating valve under the sink, before anything is opened — water and mains wiring sit close together under this cabinet. Never defeat the door latch to watch a cycle run with the door open; that interlock stops a hot spray at head height. Bail standing water out before tipping the machine, and expect glass in the sump, so feel with a cloth rather than bare fingers.
Models in the COSDWH family
Reference| Model number | Family key |
|---|---|
| COS-DWH240TT*** | cosmo:dishwasher:cosdwh |
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.
