Leaking water puzzle

[G-RMPS]

I know Hymers don’t leak but I have a water leak.

It’s the grey water, but it’s coming from underneath the location of the fresh water tank.

Both tanks are transverse but looking under the van it appears there is just one longitudinal tank. Is this an outer insulation cover for both tanks? If so it would explain why the water appears to be coming from under the fresh water tank.

I have looked inside the grey water tank but cannot see/feel anything untoward. Is it possible that grey water from whatever source isn’t even getting into the tank but is somehow escaping outside?

 

[Brains]

Are you sure it gray water ?

You have fresh water, gray water and hot water tanks also possibly a blackwater tank or cassette.
First I'd try to prove which one is leaking and under what conditions.
Does it depend on how full it is, or the angle of the van ?

It could also be the piping rather than the tank, especially where the pipe goes into the tank.
Or from the waste pipe at the sink end.
(Check that stuff in the drawers under the sink has not moved or punctured the waste pipe

With leaks the water can often travel quite a distance from the source.

Also remember at +5c the automated tank drain valve will come into effect.

 

[G-RMPS]

Fresh water remains at same level. Waste tap is permanently open and virtually nothing comes out of the waste pipe, regardless of whether it is shower or sink water. There’s a steady drip or two around the nipple or nozzle or whatever that is. The valve to release all but 20 litres of fresh water is tight. The heater tank drain is elsewhere and anyway it’s much warmer than 5 degrees.

I’ll keep looking, thanks!

PS All sources of grey water enter the grey tank via their own pipe, as expected. I suspect the drain from the grey tank isn’t sealed properly and most water is escaping into an outer shroud and from there to the ground via that nozzle.

I did clonk the grey water drain some time ago which may have dislodged the seal. If that’s the case I don’t know how to fix it unless/until I remove the the drain from the outside of the tank. Will it matter if the outside shroud is swimming with water for some time?