All caravan manufacturers use carver or whale external pumps or spinflow onboard pumps and from our experiance they are not cheap and they certainly do fail at an alarming rate, the spinflow internall is unreliable and very noisy. my first van was a swift challenger 1998 model, we bought it second hand and within 2 months the carver water heater had failled then the pump failled and then we found the floor rotten due to a leaking door seal, all the faults with this van where due to third party components.
We sold this van and bought a brand new 2002 coachman pastiche, in the first year we had two new carver pumps and three new carver water inlet housings, the van had no other faults at all.
This van was swapped in 2003 for a coachman vip 2003 model, we had another two carver water inlet housings and one whale shower unit replaced, again no other faults apart from third party components.
We swapped this van in 2004 for a coachman laser 2004 model, we some how ended up keeping the pump off the old vip so decided to keep the new one as a spare and use the old one, it lasted 6 months then failled, then once again the housing failled. this van also had to have the shower tray replaced as the door broke it due to its weight in the bottom hinge, this tray broke again just before we sold the van. once again a van that was superbly built but was let down by third party components.
Now to the van we currently own, a ace celebration 590 (based on equirry 590). the van is just seven month old its had one new carver pump a new thermostate in the heater a new tap and every single hinge on the overhead lockers has had to be replaced due to them wearing prematurely, they are now loose again. this van is not a patch on the build quality of my coachmans but the layout was just what we wanted so we gave it a try only to find its as poorly made as our first van the challenger. having said this up to now the only things that have failled are once again third party components. so don't automatically blame the manufacturer, they all use these components, even the germans, on site this weekend was a burstner with a faulty heater and a broken door hinge, it was four month old. the problematic regulaters are made by truma and i was led to believe that they have rectified the problem which aparently was much more common if butane was used instead of propane.