I have to replace my waterlogged well pressure tank. The current piping material is PVC. The wellhead outlet is 1 inch NPTF and looks to be metal. The PVC exits the pumphouse and then heads underground on its way to the house. The pumphouse also has a whole house filter stand from Express Water.

The pumphouse is remote and is semi-insulated but not heated. Some of the piping has heat tape on it. I live near Seattle so it does get below freezing at night for 5-7 days at a time but generally does warm above freezing during the day. Although there are a couple of full multi-day below freezing events. According to the meteorological records I've found, the ground never freezes.

What piping material would you recommend? PEX (specify which type), PVC, CPVC, copper? Something else?

Any other design considerations you'd recommend?

FWIW, I don't mind buying another tool (like an expander), if need be.


  • 1
    Is there another reason to replace the tank? With most waterlogged tanks, just need to drain a bit and add air and you have a tank working as new.
    – crip659
    Aug 1, 2021 at 22:58
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    Yes. It's my understanding that a bladder tank that is waterlogged means the bladder is compromised. I did drain the tank and re-pre-charged it and it is definitely working better (no short cycling). Others have said that it's a matter of time before it gets re-waterlogged.
    – coderjohn
    Aug 2, 2021 at 1:04
  • One big difference between CPVC/PVC and PEX is the internal diameter of the fittings. PEX fittings at the same "named" size flow less.
    – coderjohn
    Aug 2, 2021 at 1:19
  • For piping would not use copper or any metal type pipe in places where freezing might be possible. Would stay with one type so do not need to worry about getting the right adapters from one type to another type. If pipes not broken, keep the ones you have now.
    – crip659
    Aug 2, 2021 at 11:28
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    @crip659 Adding air to a tank with a failed bladder is a constant maintenance item...not fun, and if not done often enough, leads to short cycling of the pump which will def. shorten it's life. Also, to the OP, when you replace the tank, clean up the wiring to the pump, individual wires running along a floor are def. not code legal and not safe. Aug 2, 2021 at 12:03

1 Answer 1


Metals can leach and/or corrode, depending on water chemistry. They are also subject to freeze damage.

PVC is subject to freeze damage and sunlight damage, but inside a shed there should be no sunlight, and if you prevent it from freezing it's very cost-efficient (inexpensive) at the "make lots of joints and turns" part of well plumbing.

Black Poly (Polyethylene, but not "crosslinked" so not PEX, and cold-water only) well pipe is good for long runs, a pain for "lots of joints and turns" and freeze resistant.

PEX offers little to no advantage .vs. black poly well pipe in cold water main-line service.

My own well is black poly down the well to a stainless steel pump on lead-free bronze fittings, a bronze pitless adapter through the side of the well, black poly to the house, PVC for the whole bunch of fittings where the water comes in, with filter, shutoff, and over-pressure (bronze in a PVC fitting) a section of PEX to the PVC pressure-tank Tee and PVC split to hot and cold supply side valves, PEX from there out). The connection between the two sections of PVC used to be 1" black poly, but I found I needed a flow restrictor anyway, so I dropped it to 3/4" PEX.

The only other "design consideration" that comes to mind is that I prefer to sheathe insulated walls, as I've seen that "we'll just stop with stapling the insulation in" level of finish be far too attractive to rodents - it also makes the shed less generally useful than one with actual interior walls, e.g for storing tools or garden stuff or bikes or whatever as well as the pressure tank & piping. You could also put a layer of foam sheet insulation over the studs to improve the level of insulation, and/or box-in the water stuff in a more-insulated (openable) box inside the shed. That will minimize both the amount of time heat tape is needed, and how much power it uses when it is needed.

  • FWIW, I used PEXB when R&R the pressure tank. I would have used the PEXA but I could not find the preferred expander tool so I just used SharkBite fittings.
    – coderjohn
    Aug 22, 2021 at 22:56

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