Trying to winterize better. Copper pipe feeds normal garden water hose. How would one attach an air compressor Attachment to thread on here to blow out water line? to this to blow out? If you have better terminology for the parts pictured, that would help.

Coarse thread “1/8inch”

Picture of copper pipe with small drain cap. Drain cap blowing bubbles
Click images to embiggen

  • Usually just need to add a blow out valve on it, most hardware/plumbing stores should have it.
    – crip659
    Commented Nov 10, 2021 at 23:09
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    That's intended as a drain. Whether you can find any fittings to fit it other than the cap that comes on it is a bit of a gamble. It could be a standard thread - or not.
    – Ecnerwal
    Commented Nov 10, 2021 at 23:26
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    that does just look like a drain. Why do you want to winterize better? shutoff water at this valve, open outside to allow air in and open that drain cap and presumably any water in the line will drain out (assuming it is gravity plumbed properly) Commented Nov 11, 2021 at 1:54
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    Pipe threads are nominal for the hole inside the pipe, so the threads are always bigger than the "size"
    – Ecnerwal
    Commented Nov 11, 2021 at 13:01

1 Answer 1


Use a rubber tipped blow gun. You should be able to hold it in place, doesn't seem like something you need a threaded connection for. Blow gun

  • I lost track of this question until now. I never thought of trying a rubber tipped blow gun partly because non of mine are rubber tipped. Did not find try anything special this year, at least not yet.
    – rjt
    Commented Jan 3, 2023 at 17:17

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