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  1. #1
    Join Date
    Oct 2008
    Posts
    3

    Question water pressure drops

    After living in this house for 9 years a water pressure annoyance started about three months ago.
    When I turn on any faucet, tub, shower...hot or cold water, the water pressure reduces to about half, after approx. 5-10 seconds.
    I can increase the pressure by turning the faucet up again...then it will stay OKAY until I turn off and on again.
    Any thoughts?

  2. #2
    Join Date
    Jan 2008
    Posts
    731

    Default Re: water pressure drops

    Did you do any work to your water supply plumbing anywhere before this new problem developed?

    1) do you have a well/pump or are you on a public water system?

    2) do you have a water treatment system (softener, filter, etc.).

  3. #3
    Join Date
    Oct 2008
    Posts
    3

    Default Re: water pressure drops

    No work has been done to any plumbing in the house.
    I am on the city water supply.
    I do not have a filter or water treatment system.
    I have a 50 Gal. Gas water heater with an expansion tank. This was installed about 3 years ago. My problem started a few months ago.
    Thanks

  4. #4
    Join Date
    Aug 2007
    Posts
    1,131

    Default Re: water pressure drops

    Is there a PRV (pressure reducing valve) on the incoming supply main?

    This sounds suspiciously like a malfunctioning PRV.

  5. #5
    Join Date
    Jun 2007
    Location
    Coventry, RI
    Posts
    340

    Default Re: water pressure drops

    First thing you might want to check is the water pressure coming into the house after the meter. You may have a sillcock right near the water meter for draining the whole house. If you do you can attach a pressure gauge to it and see what you have. Ideally you want 45-55 psi coming in. If you don't have a sillcock there you can use an outside one as this should be directly off the cold water supply.

    Near the meter you may also have a pressure regulator which allows you to adjust the water pressure coming into the house. This could have been turned by say a curious child who wants to be a DIYer or is somehow malfunctioning. If you have one and tested the pressure before it and it was good you should also check the pressure after the regulator.

    Other things to look for are sediment in the screens of the faucets, valves that have been partially shut again by the curious DIYer. Hope this helps you out.

    Mike

  6. #6
    Join Date
    Jan 2008
    Posts
    731

    Default Re: water pressure drops

    Quote Originally Posted by bill w View Post
    After living in this house for 9 years a water pressure annoyance started about three months ago.
    When I turn on any faucet, tub, shower...hot or cold water, the water pressure reduces to about half, after approx. 5-10 seconds.
    I can increase the pressure by turning the faucet up again...then it will stay OKAY until I turn off and on again.
    Any thoughts?
    Quote Originally Posted by bill w View Post
    No work has been done to any plumbing in the house.
    I am on the city water supply.
    I do not have a filter or water treatment system.
    I have a 50 Gal. Gas water heater with an expansion tank. This was installed about 3 years ago. My problem started a few months ago.
    Thanks
    you could check the pressure at the drain spigot of your water heater tank as well as the temperature of water in the tank at that point.

    since you indicate that you are getting GOOD pressure and FLOW by simply opening up a spigot more AND

    you indicate that whenever you open ANY faucet, hot OR cold water you get a MOMENTARY (five to 10 second) BURST of HIGHER PRESSURE...

    I suspect that your expansion tank near your Water Heater is overwhelmed, waterlogged, or has a problem related to its charge.

    When water is heated it expands. The expansion tank you had installed three years ago is supposed to manage that expansion. If it cannot that excess pressure can back into the plumbing lines. Usually it backs up towards the cold side towards the water main it can also back into the entire potable plumbing system - both hot and cold water lines. The other byproduct of heating the water is hydrogen gas - during periods of non-water use while the water heater continues to fire heating cycles, this (hydrogen gas) can collect in the plumbing system also.

    I would 1) check the expansion tank. what you can do to check this varies on the type of expansion tank and the brand and model. 2) check the temperature setting on the water heater. 3) look for signs of discharge at the temperature and pressure relief valve on the water heater, and possibly test and inspect it for signs of mineral salts collection on the interior). I would also consider 4) draining/flushing your gas fired water heater of sediment collection in the tank.

    If you have a pressure reducing valve on your water main I would also check its screen for sediment and its setting, but I do NOT believe that is where your symptoms (as you've described them and the fact set you presented) are directing attention, although a not fully open valve at the water main (gate valves are notorious for this spinning but not fully opening or closing) and a pressure build up in the potable plumbing lines might also explain this. Do you have a mixing valve on the output of your water heater?

  7. #7
    Join Date
    Jan 2009
    Posts
    1

    Default Re: water pressure drops

    We just recently started having that problem at my house. My parents seem to have just become accustomed to less than half the water pressure but it bothers me, so I just signed up to try and find some help and this problem sounds very similar to ours.

    When turning on our faucet, the water pressure is fine for about 3-4 seconds on full blast and then a noise (almost like a knock on wood) and the water pressure drops right down. Playing around with the faucet today I noticed once the water pressure drops and I leave the sink running, if I take the water sprayer (that thing you grab to wash things out) and lift it up and down a few feet up from the sink and then back down again, the sink will begin to flow more quickly the higher up I raise the water sprayer and decrease as it goes down. The water pressure still isn't at full pressure when lifting up the sprayer, but it definately changes it. Not to hijack the thread or anything, I thought I could add some detail about my problem so maybe someone can point me in a certain direction for sure. Thanks for any help.

    -Alex

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