I'm putting in a water line from a new well to my house. I've purchased 250psi 1-1/4" CTS poly tubing, it's about a 230' run. I plan on transitioning to PVC underground outside the pump house before the line goes into the building, and also transitioning to 1-1/4" PVC sleeved in 2" PVC where the line passes through my concrete foundation under my house. I purchased these brass compression fittings to make the transition:

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There's also a stainless steel sleeve that goes inside the pipe to help maintain stiffness.

Anyway, my question is if it's safe to bury these fittings underground, or if I should plan on putting a valve box over them to maintain accessibility. The pipe will be 2' below ground, so even with the valve box it won't be easy to service it should it fail in the future.

Also, is my plan to transition to PVC sensible before it enters buildings on either end? After the PVC enters my house there will be a further transition to PEX.

  • that fitting may split if frozen while filled with water
    – jsotola
    Commented Nov 30, 2019 at 0:41
  • @jsotola will make sure to bury it below the frost line. I'm in Seattle, so it's not that big of a problem. 2' down
    – atanamir
    Commented Nov 30, 2019 at 2:04

1 Answer 1


From a corrosion consideration it should be good: Except check that the clamping screw on the CTS end is stainless steel , non-magnetic would be best. A steel screw would not likely last long on a brass/bronze fitting underground. The fitting has a more reddish color than yellow brasses which is means better corrosion resistance ( less zinc and more copper and tin). This answer if for buried in the ground or a valve box.

  • 1
    Yep, the specs state that the screw is AISI grade 304 stainless steel. Did I made a good design choice entering the buildings with PVC and keeping the transition underground rather than entering the house with the poly pipe directly?
    – atanamir
    Commented Nov 29, 2019 at 22:13
  • I would agree with keeping the poly in the ground. PVC is easy to repair where sometimes poly can be a headache plus the parts cost more than PVC.+
    – Ed Beal
    Commented Nov 29, 2019 at 22:37

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