I installed water hammer arrestors at the exact location where I had "old school" air chambers, right behind my bath tub faucet. After doing the job, I realized that the water coming from below is coming directly to the hammer arrestors (see picture). After some googling, I noticed that most water hammer arrestor are installed using a T and are somehow connected horizontally on the problematic water line.

I would like some kind of confirmation if the location of my arrestors is correct or not. If not, Feel free to advice how I should update the layout of my lines.


  • That is some ugly soldering on those lower elbows.
    – Ecnerwal
    Commented May 4, 2020 at 14:09
  • Agreed, house was built in the 70s, most of them are better than these two, but far from perfect. No leaks in 40+ years though.
    – allaire
    Commented May 4, 2020 at 15:32
  • Are they working ?
    – Alaska Man
    Commented May 4, 2020 at 16:14
  • They do help, but after a while I did get some hammering coming from the faucet, so I did the good old air trick in the system (closing the main line) and it fixed it. So I'm wondering if this because the water pressure at some point keeps the arrestors all the way up all the time.
    – allaire
    Commented May 4, 2020 at 20:04

1 Answer 1


Straight into the arrestor is ideal. The cause of water hammer is the mass of water traveling towards the valve that was shut - the more directly that connects to the arrestor, the better.

They are often only applied after a problem is noticed, in which case getting them in any which way is common.

  • Hi Ecnerwal, thanks for replying. Just for clarification, are you saying the way my arrestors are set up is the ideal way?
    – allaire
    Commented May 4, 2020 at 15:33
  • Ideally the faucet valve would be off a very short tee and the arrestor would be on top of that tee (for a vertical run) or at the end of it for a horizontal. So the length of pipe from arrestor to valve is not quite ideal, but for where they are in the system, the orientation is ideal.
    – Ecnerwal
    Commented May 4, 2020 at 23:41

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