We have 2 20 gal pressure tanks and a 40 / 60 Square D pressure switch. I was talking to my well installer and he said they typically set the tanks to 20psi and regulate the pressure only by the switch. The pressure seems to hold stead at 43 psi and cuts off at 60 psi. In the house, the pressure is "ok". It's not great.

After much reading and asking this question, I thought the tanks should be set 2 under the cut-in pressure. Am I losing pressure because my tanks are only set at 20 psi?

  • Ecnerwal's answer to your original post was pretty good. Having the air pressure in the tanks set incorrectly reduces storage capacity and is hard on the pump. Incorrect air pressure or a failed storage tank bladder might cause pressure problems, but not necessarily loss of pressure.
    – user39367
    Oct 27, 2015 at 22:43
  • @chris, I agree, but the storage would be greater having them set at 20 PSI, correct? My question was more if having them set at 20 PSI is my pressure issue.
    – DDiVita
    Oct 27, 2015 at 23:25
  • 1
    Air pressure in tank must be matched to system pressure. If the pressure is 20psi with system 40-60, the result is a water-logged storage tank that never empties and a smaller active volume of space (half the tank is filled with water just getting to 40 psi and that never empties. It is like having a pressure tank that is half as big.)
    – user39367
    Oct 28, 2015 at 4:49
  • Please see my answer below regarding a possible cause for "losing pressure."
    – user39367
    Oct 28, 2015 at 6:04

1 Answer 1


In responding to this, I am including information from your original post. (You said your well is about 100 ft from the house, that the storage tanks are next to the well, and that your plumbing is mostly PEX.) I am assuming that your house is not elevated far above your well. If it is, then you will have roughly 1 PSI additional pressure loss for every 2 ft of elevation.

PEX is sold using tubing size and not pipe size, so if there is 100 ft of 3/4" PEX connecting your well to your house, then the ID of that tube is only 0.681 inches and the pressure drop may be very noticeable. Running two fixtures or flushing a toilet while running a sink might cause 10 psi pressure drop across the run length. If the house is piped mostly with 1/2" PEX, then there would be additional pressure losses there also.

Instead of setting the system operating pressure ever higher in an attempt to compensate for this, I would suggest correctly setting the air charge in the storage tanks for the reason I mention in my comment under your post above, and then use a couple of inexpensive pressure gauges to measure the pressure at various points in the system to locate the losses. For example, use the pressure gauge at the storage tanks, put another gauge at a spigot on the side of the house, and another on a sink in the house. Turn on a tub and a couple faucets and record the pressures. If a significant amount of loss is between the well and the house, then replace that line with a larger size.

40-60 PSI is the upper operating range for many residential well systems, so I would not increase the system pressure above that if the issue can be practically resolved some other way.

  • There is very little difference in elevation from the well to the house. It's fairly flat.
    – DDiVita
    Oct 29, 2015 at 11:50

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