How to Diagnose & Fix Lost Water Pressure - Testing the Well Tank

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Water pressure loss diagnosis, first steps in troubleshooting loss of water pressure: this article describes gently shaking the well tank to determine if it contains water as part of diagnosing lost water pressure at a building. One can become easily confused by the diagnosis offered by simply "shaking" a water pressure tank. Shaking the tank can tell you that the water tank is empty but not why the water tank is empty. There may be a trick to this but we don't see how shaking the water pressure tank diagnoses a ruptured bladder or other very specific causes of the absence of water, but as a starting point, gently shaking the well tank can, however, tell us some things about the state of the building water supply system.

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How to diagnose loss of water or loss of water pressure in a building: gently shaking the water pressure tank - are we out of water?

Water pressure tank check procedure (C) DanieL FriedmanWe use this procedure often, by gently shaking or wiggling the well tank to see what's going on.

If the well tank is at its normal "full" level of water it will be heavy and chances are you won't move the water tank at all. We also know that the water pump has probably shut off at its normal "cut out" pressure recently since running water in the building will empty the well tank in just a minute or three.

If the well tank is empty or nearly so, it is quite light and can be easily moved. Recently when we were restoring water to a home that had been winterized, we tried turning on the well pump and we heard the pump motor run.

We gently wiggled the water tank and learned that it was empty, so we figured that the pump was not delivering water - in fact the pump had lost prime. We quickly shut off the pump motor so as to avoid damaging it. Then we primed the well pump. That was all we needed to do to get the water system working again.

Be careful: do not wildly shake the well tank nor any other plumbing component since doing so can cause a pipe to break or at least leak.

What Does it Mean if Our Well Tank is Empty?

The water tank could be empty simply because you ran all of its water out into the home and the water pump never came on to replenish the water supply. Some of the possible causes of an empty water tank and no water in the home include:

We discuss in detail how to diagnose loss of water pressure or how to diagnose and fix poor water pressure at Diagnosing loss of water - be sure to read that article. Some examples of what we discuss there are listed just below:

  • Loss of electrical power to the pump or pump control - nothing is running the water pump. Is power turned on? Is there power at the pump control and is there power to the pump?
  • A bad water pressure control switch on the water pump - perhaps the switch is not turning on the pump. This can be checked by manually closing the pump relay - DON'T TRY THIS YOURSELF - SHOCK HAZARD - unless you are qualified and trained. Pressure Control Switch problems are discussed further at CAUSES OF SHORT CYCLING
    Also be sure to review ADJUST PUMP PRESSURE CONTROL for instructions on how to adjust the water pump pressure control switch.
  • A bad water pressure regulator could be at fault (though not usually if the water pressure loss is sudden. Details are at WATER PRESSURE REDUCER / REGULATOR
  • A clogged water filter cause rapid pump cycling on and off - discussed further at CAUSES OF SHORT CYCLING
  • A well water supply pipe failure in the well or between the well and the building, so water is not being delivered to the home. (Or in cold climates, the line may have frozen).
  • Loss of prime in an in-building pump, or an internal pump failure such as broken vanes - the pump motor runs but no water is delivered. (An in-building pump could also run and no water be delivered if the well has run dry.) A shallow well jet pump well line could have a bad foot valve (in the well) and so be losing prime. A leak in the well line can also lead to loss of prime. See WELL PUMP PRIMING PROCEDURE and see PUMP PRIME, REPEATED LOSS of for a discussion of well piping foot valves.
  • A bad water tank bladder: on occasion a water tank bladder will collapse and stick to itself, failing to permit water to enter the well tank. See WATER TANK BLADDERS & CAPTIVE AIR.
  • A Failed Water Pump: A failed or failing in-well submersible water pump stops delivering water at all, or periodically overheats and temporarily stops working. Such a pump is probably at end of life, unless the problem is traced to a voltage, switch, or wiring problem. See WATER TANK REPAIRS. Also see WATER PUMP TYPES & LIFE EXPECTANCY.


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