What is Recommended Water Pressure??

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by wraujr, Jul 20, 2008.

  1. wraujr

    wraujr Member

    I am on city water with PRV on 1" copper input.
    3/4" copper mains thru house and 2nd floor with 1/2" taps to faucet, toilets, etc.
    2 floors with basement, 2.5 baths, no sprinklers, 5 people.

    Lived here 13 years with no problems and just bought Watts Pressure Gauge at HD and hooked to outside bib. Ran hot and cold for a few seconds to relieve any buildup and shut off inside faucets. Measured pressure at Hose bib.

    Pressure (static, i.e. no water running) is 78psi which seems high based on Google search. Drops to 72psi with kitchen sink running. With both kitchen and bath sink, PSI held around 68psi. Sounds like system works/sized correctly but PSI may be too high.

    To all you prodessionals out there, what PSI would you recommend in this situation????
  2. high water pressure

    78 psi is really not alll that bad...
    try checking it at 2am when it spikes

    you should set it at where it feels comfortable to you
    when you are showering..

    I have 110 psi and have kicked it down to 75....

    it seemed that anything under 70 did not make the shower
    heads work with much force...and I was getting comlaints from the wife.

    really anything under 65 gets pretty lack-luster and y ou are getting
    into the range that most wells work on...

    you are probably within a normal average range.

    try it at 70 and see if it still feels like it comes out with enough gusto.......
    Last edited: Jul 20, 2008
  3. Gary Swart

    Gary Swart In the Trades

    Yakima WA
    You're right, 78 psi is too much. I think 60 psi is about as high as the pressure should be, andown to 40 psi is acceptable. For what it's worth, I have mine set at 50. Be sure your expansion tank is adjusted to match the PRV.
  4. recommended water pressure???

    50 psi really seems pretty low, about like a well
    because if you turn on a few faucets at the same time
    you would get low volume at most of them...

    I suppose it is whatever you get used to in
    your area of the country....

    down the road about 4 miles away near a new water co pumping
    station on the south side they have pressure
    at ....135psi....during the day....

    their is one area on the north west side that has readings
    over 150...

    people are comming home from work and finding their
    laundry hoses have broken and flooded their homes.....

    that level of pressure scares me........

    plumbing fixtures do seem to last longer with lower pressure
    especially the life span of water heaters. and the
    high water pressures can really screw up a water conditioner.

    75 and under is fine with me, but

    their is a comfort range you need to try to find for yourself..

    go ahead and kick it down to 50 and see if you get any complaints.

    from the wife and family, then increase it till everyone is happy.......
    Last edited: Jul 20, 2008
  5. jimbo

    jimbo Plumber

    San Diego
    Most brands of regulators are factory-set at 55. I set a single story at about 62, and a 2 story at about 68.
  6. wraujr

    wraujr Member

    Great. Thats the real-world experience/advice I'm looking for. For all I know it was set lower when house was built over 13 years ago and the PRV is going bad.. (is that possible???).. I do know that upstairs we can have two showers running and everyone is happy. Plus, having spent too many years fixing things that "broke" while adjusting/tuning/cleaning, I really follow the adage "If it ain't broke, don't fix it"....

    In this case I do plan on turning the pressure down to at least 75 and probably 70. The gauge has a "max" needle so I will watch the PSI overnight.

    One other question, should I be concerned about debris breaking loose during adjustment??? I was planning on running outdoor faucet near PRV when first making turns to flush debris, just in case... Am I being over cautious/neurotic??
  7. gdog

    gdog write diagnostic firmware for embedded industrial

    Pac NW
    Just from my experience (last 3 houses where i measured it) anything in the 60 to 80 psi range is optimum (though i haven't had to deal with h20 conditioners).

    Anything less than that and the wife complains about the shower pressure; more than that and your risking washing machine, hoses, etc. exploding/leaking while you're on vacation.

    My last house the incoming pressure was only 30 psi (and the city thought that was acceptable); it was miserable.

    my $.02
  8. wraujr

    wraujr Member

    Need MORE Help and Training

    Obviously I need more help with adjusting my PRV.

    As mentioned, I ran hot and cold for a few seconds and then with all valves closed I measure 85 PSI. Turned on Kitchen faucet and pressure dropped to 80 PSI (measuring at outside hose bib with Watts Pressure Gauge).

    So, I turn Watts 35B (13 years old) PRV 1 turn counter-clockwise. No change in 85 PSI (all valves closed). But now when I turn on faucet pressure is 72 PSI instead of the 80 PSI before. Repeat with another full turn and once again pressure is 85 PSI with all valves closed, BUT turn on kitchen faucet and pressure has dropped another 6 PSI to 66 PSI.

    Clearly, moving the screw is reducing water pressure WHEN KITCHEN faucet is ON, but is ALWAYS 85 PSI with all faucets off.

    Is there a procedure for adjusting a PRV other than the obvious one?? Please help train an electrical engineer.. :)

    P.S. For what its worth, mine is a "closed" system with PRV bwtween city and house and NO expansion tank.
    Will get tank when replace HW heater. But, I ran hot and cold before test to remove any residual buildup due to water heater.. But, that made no difference in pressure.

    Should I run one faucet during pressure adjust????
  9. no faucets on

    the true reading of your side of the prv is what it reads
    without anything running....at full pressure....

    if you have cranked it down and after running the faucet for a minute or so to kill off the presure,

    if it goes back up to 85 them most likely the prv is bad,
    or you really need to crank it down five or more revolutions...to get it to work.....

    if their is no change , then change the prv....,
  10. Furd

    Furd Engineer

    Wet side of Washington State
    For what it's worth...when I was growing up the water pressure at my parent's house was 103 psi. with no PRV. It had all galvanized steel piping with the exception of chrome-plated copper tubing (using cone-shaped compression "slip" washers) to the fixtures. When I was in my later teen-age years we replaced the incoming 1/2 inch galvanized pipe with 1 inch galvanized to the main shutoff where we transitioned to PVC. We ran PVC to the cold water side of all fixtures and over the course of about a year ran the hot with copper.

    The only problems we EVER had that might be attributed to high pressure was that about once a year the copper tubing between the stop valve and the kitchen sink would blow out of the rubber slip nut coupling. We fixed that when we replaced the slip nuts with flared fittings.

    During approximately this same time I worked on some jobs in locations that had a lower elevation than my parent's house. Since the water supply to these places from from the same water system the pressure was even higher, in one case we had about 130 psi water pressure. We never had any problems at that location that could be attributed to the high water pressure.

    I have lived or worked in areas that got their water from wells where the pump setting was so low that it would barely make it to a second floor bathroom. Where it took no less than five full minutes to refill the tank after flushing the toilet. Where you would swear that you could spit more water than the shower put out. I have also lived in an area where the municipal water pressure would fluctuate between a low of 30 psi and a high of 70 psi and THAT was miserable because of never knowing at any particular time if you were going to get a spit or a deluge from opening the faucet.

    Where I live now the pressure is fairly constant, varying from a low of about 50 psi to a maximum of 70 psi.

    What all this means is that any pressure figure from 40 psi to 80 psi is probably okay. There is no "magic" number.

    Turning the adjusting screw on any PRV only one turn is going to have a minimal effect upon the dynamic water pressure in your home. All PRVs will exhibit the effect of droop or sag in pressure between no flow and maximum flow. The pressure on the downstream side WILL decrease as the flow increases, this is normal. How much it decreases is a function of what the incoming water pressure is, the size of the orifice within the PRV, the size of the piping on both sides of the PRV and the actual flow rate through the PRV. All PRV installations should have at least provisions for installing gauges on both the incoming and discharge piping if not actually having the gauges installed.

    PRVs are mechanical devices and as such are subject to failure. They can fail closed, in which case you will get no water through them. They can fail open in which case they will not regulate the downstream pressure or they can fail in an intermediate position in which case they will restrict flow giving a reduced downstream pressure that will vary proportional to the flow (high flow gives high pressure drop and low flow gives minimal pressure drop) with it passing full line pressure when all flow is stopped.
  11. blazer45

    blazer45 New Member

    Water pressure regulators are an essential component of almost every building on the public water supply. There are many different types of water pressure regulators to consider, each one made for different applications. Pressure regulators are mounted inline on the incoming water supply and can be exposed or buried.

    Water pressure regulators control both the water pressure and the flow rate of the incoming water supply. A damaged or worn out pressure regulator can result in destructively high water pressure in the building.

    Recommended water pressure in a home is 55 PSI; maximum safe allowable pressure at 80 PSI in any building.
  12. Thatguy

    Thatguy Homeowner

    In VA, minimum is >20 PSI for health reasons, goal is 40 PSI, 80 PSI is max.
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