No pressure in water tank after a few days?

Discussion in 'Pumps and Tanks Well Forum & Blog' started by jed1154, Dec 28, 2010.

  1. jed1154

    jed1154 New Member

    Messages:
    98
    Location:
    Texas
    When I leave teh house for a day or more, I usually turn off the water to the house in case something happens and turn off power to the well. I have a pressure tank on a well. Its NOT a bladder tank, just a regular 120 gallon or so. Anyway, I forgot to shut the water off to the house and when I got home, I had no water coming out of the faucets. Fearing the worst, I checked outside and finally realized my pressure tank was half full of water, but had 0psi of pressure. This was after about 4 days of no use. It APPEARS as though the pressure simply 'leaked out', and without the well on, it did not fill it to keep pressure up.

    What does this mean, is it a problem and should I do anything about it? The tank itself is probably 10 years old, and any area that is threaded for pipe or gauge is flaking off and swollen with rust, despite my best efforts of rust reducing spray paint.

    I just drained the tank in the yard to empty and fired up the well. All is well and working now.

    What say you plumbers?

    EDIT: I know it had enough water in the tank when i got home to be about 2/3 full. I could see this from the condensation on the outside of the tank. No water leaks anywhere else that I could see. If it had no water in it and 0PSI, then that would be one thing, but its strange to me to have water and no pressure. Maybe thats to be expected after 4 days of no use, but I don't think so.
    Last edited: Dec 28, 2010
  2. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,281
    Location:
    Land of Cheese
    The pump is the only thing that can provide pressure. For the pressure to fall back to zero over a few days with the pump turned off could be as simple as a faucet that dripped or a toilet fill valve leaking. There is the possibility that the pressure leaked back into the well via a faulty check valve.

    If you wanted to test it further, you will need to have a gauge installed either on the tank or tee'd into a pipe just downstream of the tank. The initial test would be to allow the system to come up to normal pressure and then close the main shut off valve. The shut off valve would be used to isolate the system to determine if the leak is upstream or downstream of the valve.
  3. Gary Slusser

    Gary Slusser That's all folks!

    Also, the old air over water pressure tank could have an air leak. That type tank is usually about half full of water with the rest filled with compressed air, which provides the power to move water when the pump is off.
  4. jed1154

    jed1154 New Member

    Messages:
    98
    Location:
    Texas
    Yes, but a leaky toilet or faucet would have resulted in nearly zero pressure AND a reduced amount of water in the tank...correct?

    I had about half a tank of water still, but no pressure. To me, that pointed to a leak, maybe at the pressure gauge on the tank, that is above the water level, letting the air escape, but not water.....

    Correct? If so, then that leads to my next question....when should a pressure tank like this be replaced? Just about every threaded section on this tank is rusted to the point of being swollen and flaky.
  5. Gary Slusser

    Gary Slusser That's all folks!

    An air leak with your air over water type pressure tank, or a water leak anywhere in the system, allows a loss of "pressure" which leads to no pressure on a pressure gauge, and now water movement out of fixtures/faucets.

    Your type (air over water/no 'bladder') pressure tank will always be roughly half full of water, above the water is compressed air.

    If it ain't broke don't fix it comes to mind but until it leaks unless you can't sleep from worry or just need a project to work on, I wouldn't "fix" it. :)

    If it isn't leaking, the rust isn't hurting anything but it sounds as if you want to replace it, so go get a good quality 'bladder' type tank at a well or plumbing supply house (found under Tanks or Pumps in your yellow pages).
  6. jed1154

    jed1154 New Member

    Messages:
    98
    Location:
    Texas
    I don't want to replace it.

    Why go to a bladder type, how could those be 'better' than what I have?? Also, won't that require changing the current well head setup with the shrader valve or something? Seems to me the bladder type would be less rugged and prone to wearing out and leaking, leaving me with the same system I have now....why not just get a tank without all the extra stuff? I guess it keeps the air and water separate, but I can't see how that is really that big a deal.
    Last edited: Dec 29, 2010
  7. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    I would agree with that, I have mostly plain tanks and they last very long. Unless you actually compress the air over the water, however, they give less than half of the storage of the bladder type per size of tank.

    You probably have a very small leak in the house somewhere, that only leaks under pressure.
  8. jed1154

    jed1154 New Member

    Messages:
    98
    Location:
    Texas
    Help me understand something....how can I have a small water leak in the house if the tank still has a full tank (half a tanks worth) of water? If this were teh case, say a toilet leaking, then the pressure would be 0 but also there would be no more than 1/4 tank of water, right?
  9. Waterwelldude

    Waterwelldude Well driller,pump repair. and septic installer

    Messages:
    303
    Location:
    Texas
    With that type of tank, the water will be about 12" or so from the top when the pump shuts off under normal use.
    Say the tank has 50psi on the gauge when it cuts off.
    If the power is shut and a sink is left running, the 50psi of compressed air in the tank will push out X amount of water until the pressure reaches 0psi. At that point there is no more pressure to push any more water out.

    Sometimes all the water is pushed out, sometimes its not. It just depends on the amount of air that is stored in the tank at the time it shuts off.
  10. jed1154

    jed1154 New Member

    Messages:
    98
    Location:
    Texas
    This is an air over water tank, and it has never in its life had more than just under half a tank at 60psi. if it did, the water would be above the pressure gauge.
  11. Gary Slusser

    Gary Slusser That's all folks!

    Your gauge will read air or water pressure and it doesn't matter which one with your type tank. Water doesn't harm the gauge.

    You seem to be having a tough time believing what we are telling you (although you don't know anything about well systems). Try this, go turn off the power to your pump. Then open all the faucets and flush all the toilets and as if it matters, then check the water level in your tank and see if you don't have about half a tank of water when the faucets etc. stop flowing water. It doesn't matter because your tank can not drain all the water unless you have a fixture/faucet below the bottom of the tank. That's because when the compressed air reaches 0 psi, you don't have any power to push 8.5 lbs/gallon water uphill.
  12. jed1154

    jed1154 New Member

    Messages:
    98
    Location:
    Texas
    I really don't know how much water is in the tank or how full it is with 60psi, probably 3/4 full or more I guess.

    I must have a leaky toilet, thats about all that can leak and not be seen anywhere.
    Last edited: Dec 30, 2010
  13. Gary Slusser

    Gary Slusser That's all folks!

    You can see if a toilet is leaking but any pipe underground you can't. Check the water level in all the toilets to be 1" below the top of the overflow tube in the tank. A T/P valve on your water heater could be leaking and you can't see it if the line is plumbed outdoors etc.
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