I live in the Atlanta area (Cobb County), and I have incoming water pressure of about 120-140 psi. I recently replaced the pressure regulator and put in a backflow preventer, and the house pressure is now set to 57 PSI.

One of the hose bibs is connected to the high pressure side, which is nice sometimes (washing the car, hooking it up to my power washer, and things like that), but it's really hard on hoses (I've had the ends come off of them)

Is it permissible to have 2 shut off valves, one after the pressure regulator and one off of street pressure, and after the valves merge them into a T to the hose bib? I could understand a backflow preventer to stop the high pressure from getting to the low pressure, as if both valves were open it would bypass the backflow preventer and the pressure regulator.

Answer:

If you defeat the backflow preventer you'll probably violate local ordinance, but only defeating the pressure regulator should be OK. If you can't tap in between backflow preventer and pressure regulator, you can put a second backflow preventer in the high-pressure line to the T.

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