I just bought a 50+ year old house. I only ever grew up with electronic sprinkler controls, and so far I haven't been able to find any sprinkler controls in the new house. However, there are exposed pipes and drip heads coming out near various plants, so I know there is a sprinkler system (or at least has been).

The following photo is the closest I could find/guess would be a sprinkler control valve. Are these sprinkler control valves? If so, how do I turn them on? I haven't tried turning them very hard yet, but the caps on the top seem quite stuck.

enter image description here

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    look for rectangular or circular covers in the ground ... that's where the valves may be installed
    – jsotola
    Jul 13, 2021 at 18:54
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    @jsotola Or underneath the stones like so many people do... lol
    – JACK
    Jul 13, 2021 at 18:57
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    @JACK and jsotola, I finally found one of the valves. It was in a rectangular box buried underneath a bunch of concrete bricks, on the opposite corner of the house from these vacuum breaker valves. And it's filled with a root ball... Jul 14, 2021 at 1:30
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    That's just your new investment's way of saying, "Welcome to your new home!" 😉
    – FeRD
    Jul 14, 2021 at 9:45
  • My valves were buried under mud and roots, I was able to totally rejuvenate them with about $100 of parts and a couple days effort. I took lots of pictures. If you post a new question with a picture of your valve box with root ball and what problems you face with it ... I might have some tips. Would be interested to know why you have two vacuum breakers ... if you ever figure that out.
    – jay613
    Jul 14, 2021 at 15:52

1 Answer 1


They are vacuum breaker valves.

Also called backflow preventer valves.

They prevent the water in the irrigation lines from being sucked into the city supply lines when city water pressure drops by allowing air to enter the supply line.

It's like poking a hole in the side of a drinking straw.

There is nothing that you manipulate on those.

edit as per @GeorgeAnderson comment

Also called anti-siphon valve.

There is also an inline backflow preventer valve does not admit air, but closes mechanically to prevent water from travelling in a reverse direction.

  • Two are relatively unusual for a home. They imply there are two controllers. Also a way to find valves ; find the controllers and follow the wires. Jul 13, 2021 at 19:21
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    I disagree, those look like anti siphon valves. jsotola, that may be just a different name for vacuum breakers, didn't mean to contradict you. :) A properly installed irrigation system would have a double check valve to prevent backflow. The actual electrically controlled valves could be anywhere, I've even seen some installed in crawl spaces. Again, like jsotola said, look for in ground boxes (usually a green cover)...unfortunately they sometimes can get completely overgrown by grass or covered with bark and are hard to find. Jul 14, 2021 at 0:04
  • Sorry, I assumed electrically controlled valves, this may be a manually operated system in which case you'll need to locate the master valve. Is there an electronic sprinkler system controller installed anywhere? Jul 14, 2021 at 0:07
  • @GeorgeAnderson you are correct about them also being called anti siphon valves ... they do prevent backflow ... like you said, there is also a backflow preventer valve that is a one-way valve and is installed inline with the water supply ... such valves have a springloaded mechanism that closes when the city side pressure drops
    – jsotola
    Jul 14, 2021 at 1:25
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    An acquaintance had a 50 yr old sprinkler system operated hydraulically. There were many 1/4 rubber hoses that operated the valves. She could not find anyone who could repair it. Jul 14, 2021 at 3:33

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