Actually, there is.
I posted this some time ago. My 2011 leaked under high pressure at the plastic intake regulator. After removing the refrigerator, I found this:
All that is standing between you and a flood is a cheap, plastic regulator held together with four screws. That's it. In my case, the device leaked because the screws, over time, either loosened, or never had been, fully tightened. Didn't matter as the damage was done. But even without that issue, the regulator itself is simply not very robust. I wouldn't trust it.
Regardless of what Airstream suggests in the manual, using a quality (i.e., brass) regulator at the tap won't cause a problem under normal pressure. And, you won't have to rely on a very cheap and flimsy plastic regulator to keep from flooding your van. If it does cause pressue issues, you can simply remove it from the line. I'd rather be over-cautious than risk a major flood if the plastic regulator fails.
But if you come to a park that has extremely high pressure, you are rolling the dice that what happened to me will happen to you. If you want to stack the deck in your favor, use a separate regulator at the tap.
Originally Posted by dkottum
Pharm, your water hoses are outside the trailer and not protected by the built-in unit. There is a good chance your hose damage occurred from expansion within the hose from heating of the sun, so a pressure regulator at the campground spigot would not have protected that either. There is really no reason to use an additional pressure regulator.