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Thread: water supply

  1. #1
    jeff boyle's Avatar
    jeff boyle Guest

    Question water supply

    Several areas that I do inspections use municipal water towers. I understand how and why they work. For every foot of height they provide around 4.5psi of pressure. Usually supply around 60-100psi depending on the amount of water in the tank. I have run into a problem with one home. Water pressure is a constant 85psi. But there is very little water flow, just a trickle. The home is in the same general area and elevation of other homes I have inspected, their water flow is fine. This is a new home 5yrs old, from my understanding the water was fine originally. The home does not have any filters connected to the system, all valves are fully open. I have talked to the local water authority about the problem, they informed me they know this home has problems but the cause is not on their end. On my report I suggested they call a plumber. I am scratching my head on this one, 85psi and no water. Any input would be appreciated
    Thanks
    Jeff boyle

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  2. #2
    Join Date
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    Default Re: water supply

    If there was good water flow at one time:
    most likely water valve at meter, or water shutoff for house not fully on.
    Defective shutoff valve(s).
    If copper supply line was used,
    damage to supply line (kink/ crush)
    line not deep enough in ground, damaged by car, equipment etc.
    foundation settling (can damage supply line)
    Tree roots (although unlikely)
    Alteration to water line that you was not informed about.
    Of course this is just a starting point and for FYI , and not for you to suggest as the possible cause(s) or correction(s).

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  3. #3
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    Default Re: water supply

    Sounds like they have a crimped line somewhere.

    Where are you checking the pressure from or its location?

    rick


  4. #4
    Join Date
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    York SC Licensed in NC and SC
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    Default Re: water supply

    All of the inside faucets have screens that need cleaning, very often in many cases. Or it could be a crimped main water line where it enters the foundation or in the yard.


  5. #5
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    Default Re: water supply

    Do they have a pressure regulator?
    A defective regulator, valve or a crushed line.
    Like Rick said, do you get the same pressure on all hose bibs?
    Just to quantify, you might take the pressure and then open another valve fully to see what the pressure drop is, and maybe a flow test.
    Plumber is the answer though.

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  6. #6
    Richard Moore's Avatar
    Richard Moore Guest

    Default Re: water supply

    Not much to add. If flow was weak at the hose bibs (no filters or aerators there), then a restriction/crimp somewhere in the main supply line. If only at interior faucets, I'd suspect a build-up of debris.

    One correction though...it's about .45 PSI per column foot of water, not 4.5 . Actually, even that figure is for seawater. Fresh water is less dense and closer to .43 PSI per foot (roughly 10 PSI for every 23').

    Here endeth the lesson nobody really needed! Sorry!

    Last edited by Richard Moore; 10-09-2007 at 11:41 AM.

  7. #7
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    Default Re: water supply

    Quote Originally Posted by Richard Moore View Post
    Here endeth the lesson nobody really needed! Sorry!
    Almost endeth ...

    inch of water column (in WC) a traditional unit of pressure, used in plumbing to describe both water and gas pressures. The conventional equivalent of one inch of water is 249.0889 pascals, which is 2.490 889 millibars, about 0.036 127 pounds per square inch (psi) or about 0.073 556 inches (1.868 32 millimeters) of mercury. inch of water gauge (in wg or "wg) another common name for the inch of water column. The word "gauge" (or "gage") after a pressure reading indicates that the pressure stated is actually the difference between the absolute, or total, pressure and the air pressure at the time of the reading.

    Units: I


    A 60 foot tall water tank would produce approximately 26 psi (at sea level).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  8. #8
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    Default Re: water supply

    I think Rick is on the right track. If it is a newer home the ground or house may have settled after construction and caused the supply line to kink.


  9. #9
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    Default Re: water supply

    Did you ask if the water has ever had been shut off at the curb box? If so, the valve may not have been fully reopened, especially if it was operated by a plumber rather than a city crew.


  10. #10
    Chip O'Brian's Avatar
    Chip O'Brian Guest

    Default Re: water supply

    Jeff at what location of home did you read 85 PSI?


  11. #11
    Jon Randolph's Avatar
    Jon Randolph Guest

    Default Re: water supply

    Water pressure and flow are not related at all. Yes, higher pressure will push water through a clean pipe and clean fixture faster and give higher flow volume, but it does't take much flow to achieve maximum pressure in a closed system. Your pressure gauge may read 85 psi and that would be an accurate pressure reading for the home. But you can also have 85 psi an a system run with 1/8" tubing. Your pressure would be great (actually a little high and I would recommend a regulator) but your flow would be almost non-existant.

    I'm thinking the same as others. Crushed line, kinked line, faulty gate valve, sediment filled line, etc. How did the foundation look, a failed foundation can crush a copper or plastic line run under or through it.


  12. #12
    Brandon Chew's Avatar
    Brandon Chew Guest

    Default Re: water supply

    Quote Originally Posted by Jon Randolph View Post
    Water pressure and flow are not related at all. Yes, higher pressure will push water through a clean pipe and clean fixture faster and give higher flow volume, but it doesn't take much flow to achieve maximum pressure in a closed system. Your pressure gauge may read 85 psi and that would be an accurate pressure reading for the home. But you can also have 85 psi an a system run with 1/8" tubing. Your pressure would be great (actually a little high and I would recommend a regulator) but your flow would be almost non-existant.
    I'm not sure what point you are trying to make there, but that first sentence is flat out wrong. The rest of what you wrote is ok.

    Water pressure and flow rate ARE related, but don't take my word for it, ask Daniel Bernoulli... or any firefighter.

    Clean pipe or dirty pipe .... large pipe or small pipe .... for any given pipe size and condition, the more pressure you put behind the water, the higher the flow rate will be through the pipe (assuming the outlet end is open to the atmosphere). If you have a closed system, the more pressure you put on one end of the pipe, the more work can be done at the other end of the pipe (hydraulics). If you hold pressure constant, at say 85 psig, then either a reduction in pipe size (cross sectional area) or an increase in pipe roughness (friction) will slow down the flow rate. An increase in elevation at the outlet will slow the flow down too.

    To Mr. Boyle, who started the thread: as others have mentioned it would help if we knew where in the system you measured the pressure and the flow, and whether the system was open or closed when you measured it. To properly diagnose the problem, you need to measure pressure ahead of the restriction while you are measuring (or observing) flow rate after the restriction. In this situation, the system needs to be open and flowing when you are measuring the pressure. Taking static pressure readings on a closed system also provides you with useful information, but that's not what is needed to diagnose the flow problem. If, when you run the water, the flow is low while the pressure at a point upstream remains high, the problem is most likely caused by a restriction somewhere between where you measured the pressure and where you measured the flow.

    Last edited by Brandon Chew; 10-12-2007 at 06:58 AM.

  13. #13
    jeff boyle's Avatar
    jeff boyle Guest

    Default Re: water supply

    Thanks to all for the plumbing lesson
    The pressure reading was taken at (2) outside hose bibs, laundry tub and an out building
    They all read 85psi with the system open, closed the pressure was higher
    I did recommend installing a regulator, and a plumber on the report
    The plumber doing the repair work, came up with the same results, he suspects a crushed supply line



  14. #14
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    Default Re: water supply

    Quote Originally Posted by jeff boyle View Post
    The pressure reading was taken at (2) outside hose bibs, laundry tub and an out building. They all read 85psi with the system open, closed the pressure was higher
    To me, with that new information, it sounds like an internal problem somewhere.

    If you 85 psi *WITH THE SYSTEM OPEN* (meaning to me that the water is running), if there was a crushed water service line, the pressure would drop to very almost nothing upon opening any water faucet as you would be losing what little water was getting past the bad service line, thereby losing the pressure.

    However, if the problem is internal to the house somewhere, you would still have pressure, just not much flow.

    Did you check the water meter flow indicator for signs of leaks with everything off? With "closed the pressure was higher" that much pressure, there could be a leak in the system (under the house?) which is bleeding off some pressure and flow???

    Still, though, with 85 psi, even with a leak, you should have good flow (and maybe you do - at the leak).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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