The water pressure delivered from our provider is in the 38-42 psi range. It's gravity fed and they can't/won't increase it. I installed a Davey BT14-45T2-USA pressure booster pump to increase the water pressure and it works great with one exception: The water pressure on the side yard is down to a trickle. It was fine prior to installing the pump and it is still fine if I close the pump off from the system using the two shutoff valves and open the shutoff valve on the main line to essentially revert it back to how it was before the pump was installed.

Since the pressure on the side yard is fine when I revert things using the shutoff valves, I know it's not anything on that branch of the system like a clog, leak, etc. There is a pressure reducer valve on the side yard branch, but it's open plenty as evidenced by the pressure when the pump is closed off from the system.

With the pump on, the pressure everywhere else is now much higher, including at the hose bib shown in the photo. The main line is 1" copper. The side yard is a mix of 3/4" copper and PVC.

I don't understand why the pressure is so low on the side yard. Anyone have any ideas?

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  • That's a weird one alright. Sounds like the side yard is on the intake side of the pump, despite what's pictured....
    – Ecnerwal
    Jun 5, 2021 at 1:32
  • The side yard T shown in the picture is the only connection to that branch of the plumbing. It's definitely not on the intake side. I was reading about "fall-off pressure" for a PRV. I'm wondering if that PRV on the side yard branch is causing the problem.
    – JMellor
    Jun 5, 2021 at 1:38

2 Answers 2


I removed the side yard PRV and replaced it with straight thru 3/4" copper and the problem went away. I guess that PRV (range 10-70 PSI) could not handle the increased pressure from the pump and somehow over-reduced the pressure to the side yard.

Afterwards, I measured the pressure from a hose bib on the side yard and it's at about 95psi. Maybe I'll redo it to branch to the side yard after the main PRV.

Thank you Ecnerwal and Jasen for the responses!


maybe that valve with a missing handle is partially closed or blocked with something.

  • If you're referring to the valve on the pipe going to the side yard, the handle is not missing - it doesn't have one. You adjust it by loosening the lock nut and then loosening or tightening the screw to decrease or increase the downstream pressure. It's open enough to get full pressure. When the pump is closed out of the system via the shutoff valves, water flows through that PRV and pressure is fine on the side yard.
    – JMellor
    Jun 5, 2021 at 17:08

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