Flat water line hose on 2022 Tab 400

dvmmike

Can anyone tell me why this hose is flat? Doing some routine inspection and cleaning between trips and found this. Is this hose pre-pump or post-pump?
I have not had any water pressure issues. The only water issue that we noticed recently was during our last trip 6 weeks ago, the cold water suddenly became hot before gradually returning to cold again. Can’t recall if we were on city water or boondocking at the time because we stayed in a few different places. 

pthomas745

There have been a couple of stories about this sort of thing.  This can be a bit confusing to sort out.  

https://tab-rv.vanillacommunity.com/discussion/18475/pump-runs-but-no-pressure-water

https://tab-rv.vanillacommunity.com/discussion/18164/water-pump-pex-choices

MuttonChops

dvmmike said:
. . . Is this hose pre-pump or post-pump?

Your 'flat hose' is pre-pump; between the fresh water tank and the pump and controlled by two Nautilus valves. Reading over the threads in pthamos745 comment . . . general belief for this failure is turning on the Pump when the Nautilus Valves are set to CITY water as both the White and Green Handle valves would be Off so the pump sucks first any hose water then collapses the hose.

Note in this figure how the White and Green are set blocking flow to pump, light blue lines to pump


Basic mapping of Nautilus back side:

dsfdogs

I'm 99% certain that happened to me when I turned on the pump but hadn't changed the Nautilus to "dry camping". I was able to squeeze the hose to get it back round again.