What is this gray thing thing on a main water line - right after it comes into house?

this is private well, I should have clarified.

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  • Well or city water? The well-doily below it and wires heading the same way suggests well, but please verify.
    – Ecnerwal
    Mar 9 '15 at 16:04
  • 1
    @Ecnerwal yep - private well
    – Dannyboy
    Mar 9 '15 at 16:05
  • Are there any markings other than the "use teflon tape only" label??
    – Ecnerwal
    Mar 9 '15 at 16:42
  • @Ecnerwal I'll go and check it out later, I can't do it right now - Im at work:) Thanks for your response!
    – Dannyboy
    Mar 9 '15 at 16:43
  • 1
    Is that a tubing port on the bottom (white piece)? I've seen adapters that allow an injection line (3/8" poly tubing) to be inserted within an existing larger pipe (basically saving you from digging a trench to the well), and wondering if this is one of those. Similarly, if it's an electrical connection, it could be a heat tape connection (which are all proprietary) -- they typically have a pigtail coming off as opposed to a connection, but maybe the wire has been cut off?
    – gregmac
    Apr 8 '15 at 20:43

I can't find one that looks exactly like that, but the two most common items would be

  1. a check valve (one way valve) (might have an arrow molded into it)
  2. a "constant pressure valve" (slight misnomer) - a pressure regulator with a slight, intentional leak - used to keep your pump running a long time at constant pressure (say 50 PSI) while you are using water, and then let it slowly "leak" up to 60 and shutoff, whereupon it will drop down to 40 and turn on, then rise to 50 and stay there until your water use becomes low or none and the cycle repeats.

If you watch the pressure behavior as you use water the second one should become clear, if it applies. Or it could be something I haven't met/thought of. Possibly a (disused) chlorine or other chemical injector given the fitting on the bottom? Or an air injector if you have very antique pressure tanks with no membrane/bladder.

  • Thanks. you're probably right - I'll check out later if it has any additional markings on it.
    – Dannyboy
    Mar 9 '15 at 16:48
  • there were no other markings on it.
    – Dannyboy
    Apr 9 '15 at 17:50

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