I have my system winterized every year, when I started it back up this year, I noticed a pretty significant leak coming from under the circled black circular thing on top of the system (see picture attached). This happened when I opened up the water valve in my house and then opened both valves outside. I haven't noticed this in the past so I think this is the first time. I am not sure where to begin. Each time I open up the right valve, which I believe is the one that allows water to go to the sprinklers, it leaks. I have posted a picture and not sure what other info you need. Any help you can provide would be greatly appreciated. Thanks!!

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    Is it an automated sprinkler system or a manual sprinkler system? Could you also post any identifying information on the red plate? From the image it's hard to read what's written but might help in identifying what the part is and what could possibly me leaking. If I had to guess, I'd say that the black unit is either the sprinkler pump or a filter housing and that the (rubber) gasket/seal/o-ring or one of the connections is leaking. Possibly some water was left behind within the unit and if it froze during the winter it could have been damaged. May 30, 2018 at 11:19
  • Thank you! What the red plat says is 800M4, 1" Watt Regulation. I just opened it up and there was a ton of debris in there so I cleaned out and will replace o-ring and if not, will look for a rebuild kit.
    – G Buesch
    May 30, 2018 at 22:22

1 Answer 1


That part is probably an anti-siphon valve, required by code for sprinkler systems. These have a one way valve which prevents back flow of water in the sprinkler piping from flowing back into the house in case of a pressure reduction in the house. Turn off the water to the sprinkler system and open up the unit and examine it.

Simple cleaning of the seal may restore functionality, but you can get rebuild kits for these anti-siphon/back-flow valves. I think it has a replaceable seal which may deteriorate.

  • Thank you so much! I cleaned it out and will replace o-ring first then look for rebuild kit as well.
    – G Buesch
    May 30, 2018 at 22:21

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