It’s probably the backflow prevention assembly on the sprinkler system, from the description. State law requires annual testing. It keeps the bad water in your sprinkler system from getting sucked back into the water supply system and making everyone sick.
Yeah, that’s it...I’d like to get rid of it...we really don’t use the sprinklers...they were installed by the builder...for this spec house.
Secondly, how often (if you know) does a backflow that’s tested show a problem?