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Question DetailsAsked on 8/23/2013

How can I determine if well pressure tank pressure loss is from leaking bladder or problem in well?

House disconnect from system via shutoff valve. Pressure drops to zero over several minutes. Pressure tank reads 10-12 psi and won't take more from hand pump (tiring, by the way) or electric compressor. When pump is restarted pressure jumps to 10 psi then slowly increases to 40 (switch is 20/40); during this time water can be heard surging back into pipes and tank (but not house plumbing since it is isolated.

Any advice appreciated before I start replacing pressure tank........

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Voted Best Answer

Ohhh, and you were SO close to solving the problem yourself. You say the pressure drops off gradually after the pump shuts off - assuming the valve to the house is truly shut off all the way and you have no leaks around the pressure tank area, the water has to be going somewhere, right ? And you say you can hear the water coming back into the pipes when the pump is turned back on.

This is NOT a pressure tank problem unless it is actually leaking the water or air cushion out, which you would clearly see or hear. A pressure tank problem (lack of air cushion) that does not involve leaking causes rapid pump cycling on and off, because as soon as there is any demand for water the pressure drops off because there is no stabilizing air pressure "on top of it", which is what the pressure tank does to absorb pump surges (especially on positive displacement (piston) pumps) and prevent rapid pump cycling.

100:1 odds the foot valve is leaking - it is a one-way backflow preventer valve on the bottom of the drop hose in the bottom of the well (if your pump is surface mounted) or on the bottom of the pump (if submersible).

To test this, if you have a shutoff valve on the incoming pipe from the well, do this:

1) run system up to pressure, with house still shut off

2) shut off pump (or let it shut itself off)

3) immediately shut off the valve on the incoming pipe.

You should notice the pressure stop dropping, because you have shut off the return flow of water into the well.

4) Open the valve again - you should hear the water start flowing back down the pipe into the well - if you hold your ear to the pipe or valve there should be pretty clear sound of water flowing through it.

5) Another way to test it - if the pressure tank is being filled with air (you say it will take about 10-12 psi,, once it reaches that point I bet (with pump off) you will hear air gurgling in the well, if you canopen the top. I would bet you have about 20' of water depth over the foot valve, which is why it will build 10-12 psi but no more, because at that point the air pressure is overcoming the water pressure at the valve. The reason it took so much effort to even get that is you were pumping the water back down the system to the foot valve faster than it wanted to run down, so sort of like hand-pumping a water sprinkler.

Occasionally the installer cheats, or a homeowner want to be able to change out the backflow preventer without pulling the pump (especially if a deep well), and a backflow preventer is put in right before the pump or at the top of the well, which you might be able to change out yourself. The water in the line between there and the bottom of the well will still drain back every cycle, so the pump initially pumps a few gallons of air out of the suction pipe before water fills the lines (which is hard on the pump, requires a high-pressure air vent in the system, and makes for a lot of gurgling and bubbles in the water).

To fix - if a surface pump, you may have flexible or rigid suction pipe into the well. Flexible plastic you can sometimes pull out by hand if very flexible, unscrew foot valve with pipe wrenches (looks like a giant bicycle valve stem inside a stainless or bronze wire screen), and clean (if jammed) or replace (more usual case) - about $50-100. If drop line is very stiff or large or well is more than about 20 feet deep, then you need a well service company. Ditto if submersible pump - rarely can an individual pull this without an A-frame and hoist unless very small, particularly if you live in an area with winter frost penetration and have a pitless adapter.

Answered 7 years ago by LCD

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