well water pressure pulsates, pump loses prime

Old 11-29-19, 07:21 AM
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well water pressure pulsates, pump loses prime

Hello everyone. I have a water well, of which the pump and tank are located in a concrete bunker in the ground. I don't know much about these systems, but I have learned quite a bit over time. I believe my tank is a bladder type and was told by my neighbor that it was installed about 7 years ago.
About a month ago, I noticed the water at my kitchen sink was pulsating. I didn't know what was causing it but a week later, one minute we had pressure, and the next minute we had no pressure at all. I went to the well to check the pump. It was running but no water pressure. I turned the pump switch off, then I opened a bleeder fitting in between the pump and the tank, and noticed the inside of the pipe was completely dry. I decided the pump had lost it's prime bud didn't know why. I primed the pump, but still had pulsating water pressure. Yesterday, it did it again. I primed the pump again but still have pulsating pressure

Can anyone suggest why the water pressure is pulsating, and why the pump is losing it's prime? I've checked for water leaks, and made sure the tank drain faucet wasn't leaking. My home is a 70's modular with plastic water pipes. I replaced the hot water tank a year ago, but had to use those Sharkteeth adaptors, which I'm not fond of. One of those might be leaking but they are located in a real tough place to inspect but I;ll check those later today. Also, is there a way to test the tank? Any help would be appreciated very much.
Old 11-29-19, 07:47 AM
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When you say the water pressure is pulsating, I assume you mean higher and lower at the tap. Can you tell if it shoots air out of the tap with the water? Also, do you know if the pump is cycling on and off when you have this pulsating water?

I would drain the system (leave a tap open) and measure the air pressure in your bladder tank. It should be 2-3 psi below the cut in pressure level of your pump. I would add or remove air accordingly. If a tap is open and you have a hard time getting numbers much higher then zero, then it is an indication that your bladder in the tank is ruptured. If it is you need a new tank.

I would then re-prime the pump. When you have the pump full of water, leave it for 5 or 10 minutes to see if the water level stays full in the pump. If a little goes down after 5 or 10 minutes, add more water and wait again. If the water will not remain level, you have a leak. If it does remain fairly level, put the pump nuts back on and fire up the system. When the pump shuts off at the cut out pressure. Leave the system for a while . If no one is using water the water pressure should remain the same. If it is lowering, you have a leak.

Let us know how that goes. My initial thought, to the pulsating pressure is that your bladder is ruptured in the tank and you would be losing air pressure because of it. With lower air pressure you would get less water between pump cycles, eventually the pump would start short cycling (quickly going on and off) as you are using water. This short cycling would show up as pulsating water pressure...and a lot of noise outside by the pump as it goes on and off. I am assuming you have a jet pump, because you said it was above ground.

That would not explain why you lost prime. Usually that is caused by a leak. So my best guess at this stage is you have both a leak between the house and the bottom of the well AND you have a ruptured bladder in your pressure tank. A leak in the house, by the hot water heater for instance, would just end in the pump cycling on when you were not thinking you were using water. You should not lose prime in that situation. This would also happen if the leak was between the house and the well bottom but not necessarily if it was a large leak. A large leak in the house would almost always be noticed but not necessarily in the line going to the pump and well.

If the air pressure in the tank is OK, which would rule out that for causing short cycling of the pump, then my next guess would be a dirty line between the pump and the pressure switch. If that line becomes clogged up with debree, it can really mess up the pressure switch and perhaps that is short cycling your pump. Obviously we still need to confirm that your pump is even short cycling. That is also a guess on my part.

Last edited by OptsyEagle; 11-29-19 at 08:12 AM.
Old 11-29-19, 08:14 AM
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One last thing. I am making a lot of guesses above. It would help if you gave us a little more information on your water system:

- type of pump, jet or submersible
- if jet pump, is it deep well (2 lines coming into it from well) or shallow well (1 line coming into it from well)
- how deep is the well and where is the water level reached and where is the foot valve positioned, if you know.
- size of pressure tank
- cut in and cut out pressures for the pump's pressure switch

Just a general question. How cold has it been in your area lately. Is it possible you have ice in the line just before the pump.
Old 11-30-19, 10:10 AM
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A few pictures of what you there are helpful too..... How-to-insert-pictures.

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