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We would like to increase the hot water pressure in our home to increase the flow rate in our upstairs shower.

We are in California on city water (no well). I spoke with the water company and they said we are on a gravity fed system and it is not possible for them to increase the water pressure. They calculated the water pressure at our tap at 38-43 PSI.

I have done the following:

  • Pressure regulator valve (located near hose bib in front of house before water pipe enters the home) is wide open (maxed out at 80 PSI).
  • Water pressure at hose bib in front of house, after the PRV, before entering the house is 38-40 PSI.
  • Water pressure at cold water inlet to the tank hot water heater is also 38-40 PSI.
  • I bypassed the water heater by connecting the cold water inlet flex hose to the hot water pipe going into the house and the water flow was the same at the upstairs shower. This rules out an issue with the water heater.
  • Removed shower head and observed same slow flow rate. It's not the shower head.
  • Checked aerators at faucets and did not find any significant deposits.

I am considering installing a water pressure pump (like SEAFLO 33-Series or similar, or a more expensive Davey brand pump). Some questions:

  1. Would such a pump improve our hot water pressure for our home?
  2. Do I need a water holding tank for such a pump, or can it work without it?
  3. If I'm just trying to increase the hot water pressure, where should I install it - before the cold water inlet to the hot water tank, or after the hot water outlet of the water tank?
  4. What type of lifespan should I expect from these pumps?
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    If you have 38 PSI and are not getting adequate flow there's something wrong with the piping or valve, IMHO, given what else you have already checked. While you can band-aid a pump onto the system, sorting out the root problem would involve less operation and maintenance costs going forward. I'll link one of the answers where I detail the whacky problem I found at one house. Here we go: diy.stackexchange.com/a/49174/18078
    – Ecnerwal
    Nov 15 '20 at 21:21
  • What pressure do you get at the hose bib while simultaneously running water elsewhere in the house?
    – brhans
    Nov 15 '20 at 21:35
  • Why would you have a PRV on a gravity fed system? 80 psi is at the range I like my pump set up to, my pressure switch is set for 60/80 I removed a large pump a while back and need the pressure to water my fields and have had no problems.
    – Ed Beal
    Nov 16 '20 at 1:46
  • @Ecnerwal, thank you for that input and the link. I am concerned about the operation cost and maintenance of having a pump, too. That story you linked could definitely be my problem. Not sure if I'm up to start tearing up my walls, though. Not sure what to do...
    – JMellor
    Nov 16 '20 at 16:10
  • @brhans, I did your test and saw the pressure drop 1-2 PSI temporarily, then it seemed to go back to where it was.
    – JMellor
    Nov 16 '20 at 16:11
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If the PRV is adjustable (most are) crank it up! Normally turning the adjustment screw clockwise will increase the pressure. If you have a pressure gauge crank it to 60 most well systems I set up are 40/60 but city water I usually set 60 as a minimum. The increased pressure will increase the flow the pressure depends on the height of the tank but if you have 80 psi outside you should be able to get the same or a reasonable 60 psi in the home by increasing the Spring tension on the PRV (PRV is a fancy name for a pressure regulator they need to be made for potable (drinking) water systems but that’s all they are) increase the spring pressure and your pressure increases.

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    the PRV is already fully opened.
    – JMellor
    Nov 16 '20 at 17:54
  • If you have 80psi at your front spigot and the PRV is maxed out Its time to replace it. I would comment if your main pipe is 3/4” many times I have gone to a larger size valve 1” or 1-1/4 to provide larger orifices and less restrictions the larger size cost more but if you start getting close to your total head pressure of 80 a larger valve will provide very close to that pressure but if a smaller valve is used you may not see 60 psi because of the internal restrictions.
    – Ed Beal
    Nov 16 '20 at 22:00
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    I only have 38-43 PSI delivered to my house according to the water company. I've measured the pressure with a gauge at the hose bib and it is in that range. I mentioned 80 PSI because that is the top of the range for the PRV - sorry for the confusion.
    – JMellor
    Nov 16 '20 at 23:14

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