Plumbing flow and pressure problems in a new house

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New Member
Jan 24, 2023
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Portland, OR
I'm a contractor who just built a brand new home. It has all new water supply piping, all new fixtures. It's a 3.5 bath house with one kitchen, one laundry room. There's a 3/4" meter at the street. There is 59 PSI of pressure at the meter coming into the house.

We are experiencing a dramatic reduction in pressure and flow to the two upstairs bathrooms, especially when more than one fixture is running at time. We're losing about 15 PSI of pressure in less than 20 vertical feet of rise between the basement where the water comes in and the second floor bathrooms. Our plumber swears that every pipe is sized according to standard residential plumbing best practices.

What would be the best way to troubleshoot the pressure and flow problems? We need to be able to have multiple showers and a washing machine or kitchen sink running at the same time and still maintain decent pressure. What would you do to improve this? Would a booster pump be a solution? Would paying the city over $10K to come out and increase the meter size from 3/4" to 1" be the best path forward? Could it potentially be an obstruction somewhere in the system? Does it sound possible that our plumber is lying about having sized the pipes correctly? Would really appreciate your expertise and feedback!


Supporting Member
Feb 9, 2021
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United states
You lose ,43 psi per ft of rise.

So at 20’ you’d lose 8.6 psi.

The size of your pipes or valves has no affect on static water pressure.

If you’re having low volume/flow problems look for a valve not turned on all the way or debris in the piping.

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