Originally Posted by NWJeeper
RVs are plummed with all the same PEX so no matter if motorhome or trailer. The things you see on the water spiggots at campgrounds, the "little brass things" are not pressure regulators, they are anti siphon
and or frost free fittings used in really cold climates. The "125 psi" you see on the side is a maximum safe pressure they can allow through them. My "frost free" outdoor hose bib came from the store with the same thing on it. With most of them you will notice that if you turn off the water with the hose still connected, water will spray out the side of them, therby removing the possibility of siphoning water back into the system and draining water from the bib so it cannot freeze.
Thanks, Jeeper, for helping me make sense of that. I didn't know what it was, but when I saw the 125 psi, I knew it was too much pressure for me. Thanks again for sharing your experience. It is invaluable.