Our well pump switch works fine, kicking in at about 30 psi. As soon as the switch turns on, the water pressure immediately drops off the scale and stays down for about 10 seconds. At that point, the water pressure goes back up to normal.

Could a check valve between the pump and the accumulator cause any problems?

EDIT: Here is a picture. The yellow arrow points to where I'm thinking. well and accumulator plumbing

I'm not convinced it's just the pump taking too long to get water pressure up, because when the gauge at the bottom of the picture reaches 30(ish, from memory), the pump switch switches on, and the gauge immediately drops to zero. (Faucets or anything else looses all pressure, too) The pressure just before this drops steadily.

UPDATE: So I tried checking the pressure. I turned off the house valve (green ball valve), turned off the pump power, and drained the water using the spigot until it gurgled (no longer dropping pressure and now putting air into the pipes). The tank pressure at that point read 45psi. The pressure switch is set for 40-60, and the card that is barely visible on the top right of the blue tank says the tank pressure should be 38 for that setup. I dropped the pressure down to 38, but I'm not sure that helped.

  • Hello, and welcome to Home Improvement. It isn't clear what pressure you're talking about; would you add a picture or diagram of your system? Aug 7, 2019 at 1:23
  • A diagram showing what you actually have would be helpful, rather than asking if a valve which you don't clearly specify that you do have or don't, at the specified location would cause a problem.
    – Ecnerwal
    Aug 7, 2019 at 2:34

1 Answer 1


Lacking any details (feel free to edit your question and add them) about your well pump type (suction, jet, submersible) or location, this mostly sounds like an improperly pre-pressurized accumulator (pressure tank.) If the pump kicks on at 30 PSI and the air side of the tank is not set at 27 or 28 PSI, the water in the tank may run out before the pump gets going, producing symptoms as you see.

If you turn the pump power off and drain water from the system, the pressure on the air side of the accumulator should be 2-3 PSI below the cut-in pressure. That 2-3 PSI allows for water to be supplied while the pump gets going. If your pump is submersible this is an easy check. If your pump requires priming to restart, it's a more involved check, as you'll have to prime the pump.

  • It is a newer accumulator (installed by the seller as an attempt to fix a contamination problem found during the purchase inspection). I'll see if I can try the drain + pressure test this weekend.
    – Foozinator
    Aug 7, 2019 at 15:57
  • Looks like a submersible setup, (pump presumably in well) so the check should be easy. I would NOT suggest adding a check valve - I'm firmly of the belief that "the single check valve at the pump itself should be adequate, and additional ones can cause problems" - and it does not sound like the check valve on the pump is not working (in that case you'd have the pump constantly cycling as it leaked down, even with no water being used.) When that valve fails, the correct solution is to pull the pump and fix it. I'll stand by my explanation of what's happening now.
    – Ecnerwal
    Aug 8, 2019 at 12:09
  • When you turn on a faucet does the pump start right away and when you close it stop in a short period of time? If so you are what we called in my day water bound. That simply means there is not enough air in the accumulator/bladder. Adding Air should help solve it unless the accumulator is to small. Changing the accumulator because of contamination, does not compute.
    – Gil
    Oct 21, 2022 at 15:29

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