I just changed the pressure switch on our Pentair Shallow Well pump. We've had it for about 2 years. We've been having well problems for a while. Before the original switch shorted, our water worked fine, but then that switch shorted because of a leak in the main water shut off switch nearby where the well is in our crawl space/basement. I replaced the water shut off valve, and then replaced the pressure switch. I had heard that using a low pressure 30/50 switch may help, but our water was constantly dying and would lose pressure really fast. I've now installed a 40/60 switch that was originally included with the pump, along with a new pressure gauge. The pump will turn on. I have primed it with water first, and when I run it I can open up the valve on the top of the pump and it is still full of water, and the pump builds up 0 pressure whatsoever. I did forget to drain the tank and check the PSI with a tire pressure gauge first. I am going to be doing that today to see if that works, but if it doesn't, where should I start diagnosing next? It's a 100 year old house, shallow well in a swampy/marshy bog area. the well was apparently hand dug and does not appear to have casing around it, but there is concrete floor around it. The pipes are all galvanized steel, and one of the check valves has cracked before and had to be replaced.

At any rate, since it's winter, it is not ideal to do that right now, and I'm also curious if there might be something I can do in the meantime to get it to draw pump water again. I've tried to be thorough here. I'm not precisely sure which Pentair model it is. There's just the one pipe coming from the well up to the pump, and the output pipes, and tubes from the pressure tank. It's not a huge pressure tank, maybe like 3 ft across. This was all here when we moved into the house, except the pump which replaced an old Red Lion pump. We had a well guy come out to do that, and he said he thought that there might be a crack somewhere in the drop pipe and that he wouldn't be able to do anything about that. The more I have learned about wells, the more suspect that statement that seems. We have had a second opinion, and they said that our well might be going dry...in a swamp. A third opinion said that notion is ridiculous.

Could it be the impeller? That I forgot to drain the tank, and it's not calibrating correctly? Or crack in the drop pipe or foot valve issue? Could what is most likely be discerned based on this info? Thanks to the kind soul who reads and perhaps responds.

  • "Is it worth it?" is an opinion based question that only you can answer and is, therefore, off-topic - please edit to remove that. Are you actually not getting any water flowing or is it just that the gauge is reading 0 PSI? If you've got water flowing, then I'd suspect the gauge.
    – FreeMan
    Mar 1, 2023 at 18:34
  • @FreeMan noted and removed. I prime the pump, run it, no water flow. Then when I take off the top valve again, it's full of water, and at best a little bit of water flows out from the top where I primed it. In the past when I've opened up the top valve to prime the pump it's sort of sprayed everywhere, even after only a minute or so.
    – Josie
    Mar 1, 2023 at 19:03
  • Let's investigate/eliminate Freezing. Did you had freezing temp recently ?
    – Traveler
    Mar 1, 2023 at 19:07
  • @Ruskes we did for a few days in rural Minnesota. It's been uncharacteristically warm this year though. There was a few days where we were without heat waiting for our energy assistance to kick in though.
    – Josie
    Mar 1, 2023 at 19:23
  • Thank you so. to your knowledge there was no frost. Next test, there is no suction (it is clogged), you said when you prime it the water level stays the same? Maybe try using high pressure water hose to unclog it.
    – Traveler
    Mar 1, 2023 at 19:31

1 Answer 1


I think your foot valve is defective. Normally, a foot valve at the bottom of the drop pipe allows water to be sucked into the pipe but not to return to the well from the pipe. I think your foot valve is stuck in the open position so it allows any water in the drop pipe to flow into the well.

This would explain why your water "loses pressure really fast." The water in the pressure tank returns to the well when the pump stops.

Also, normally when you prime your pump, you are filling up the drop pipe and the pump. But if the foot valve is not holding pressure and allowing the drop pipe to fill completely, the pump is not really primed -- as soon as the water in the pump leaves the discharge, it sucks air from the drop pipe and "the pump builds up 0 pressure whatsoever" as you said.

So you should pull up the drop pipe and check the foot valve, and if defective, replace it.

  • That said though, I suspected that the foot valve has been bad
    – Josie
    Mar 2, 2023 at 2:28

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