I've had (yellow) flat water hose for about 15 years since they first appeared at caravan and camping show. Mate imported them from Germany. Expensive then, but still works fine, so probably paid for itself. New ones on reel would be even better (easier to roll up). Wouldn't use them for a mains pressure connection though. They're not that flexible when full of water and easily kink.
My sullage hose is in 4 sections with joiners. Like Bushman I suspect, one length slides into each side chassis rail from rear of van. One pce goes into the chassis cross member just behind the drawbar, and one shorter pce in the locker. Depending on site I can run to sullage or garden/trees as appropriate without having untidy coils of hose. My flat hose goes in the locker for filing tanks if I need extension. I also have a drinking water hose with brass fittings which goes in bag on top of spare (held in place by a second Jayco tyre cover).