JoeSpareBedroom wrote:

Why should they have a pressure reducing valve?

Bob

Because in some locales (like right here at my house), the unrestricted
water pressure may spike to 100-125, and even if you don't mind your pipes
slamming, some appliances and devices might have issues with.


Same thing here. I have a 120 PSI gage on the line and daytime pressure
was just fine. One time I happened to look at the gage in the middle of
the night and it was pinned because with low water usage the public
water supply pressure drifts up. I used to frequently change o rings and
washers in valves. I installed a regulator and can't remember the last
time I had to tinker with anything.