Is there a way to determine if my sprinkler system has a pressure regulator installed?

My neighbor and I both built our houses with the same builder at the same time, but had different landscaping contractors do the sprinkler system installs. His yard has 10 zones with about 7 sprinkler heads each, whereas mine has like 17 zones with no more than 4 heads per zone. I should note that NONE of the sprinkler bodies (mine nor my neighbor's) are pressure regulated.

Anyhow, I added a single head to one of my zones and my system does not have enough pressure to allow for the the additional head to function properly. It seems odd that I don't have enough pressure to supply 5 heads on a given zone, while my neighbor has enough pressure to supply 7 heads on a given zone. We're even using identical sprayheads (Hunter Rotators).

The only thing I can think of is that I've got a system wide pressure regulator installed somewhere on my system, and my neighbor doesn't. But how can I know for sure?

  • Are you on city water or a well? If on city water you both have the same pressure at the main so you must have a regulator some place. Unless your system is plumbed with 1/4" and your neighbors is plumbed with 1/2"
    – Ed Beal
    Jul 22, 2018 at 16:47

2 Answers 2


The size and configuration of the entire piping system that supplies your irrigation setup, from point of entry to your property (usually the water meter) all the way to each sprinkler head, along with pressure, determines how much water is available. Pressure is just one piece of the puzzle.

If there is a regulator on your system it would typically be found on the main water supply pipe, between the main municipal supply/meter and your home (upstream of everything, basically). You should understand that regulators are installed for a reason; removing, bypassing, or adjusting it could cause complications up to and including failure of system components (i.e. flood). Normally, if high delivery pressure necessitates installation of a regulator, then all your neighbors would have one as well. It would be prudent to do some asking around. Regulators usually look something like this:

enter image description here

In the end, the cause of your problem is usually due to undersized piping. the fact that your neighbor used a different irrigation installer and seems to have no issues points to that as well. You would be surprised at how much more water flows through a 1" pipe compared to a 3/4" pipe: enter image description here By taking pressure measurements (both static and with water flowing) and noting pipe sizes and configuration, an educated layperson (and certainly a landscaping professional) could diagnose the issue fairly quickly.

  • Jimmy, your response is about as thorough and insightful as anything I could have hoped for. Thank you. I never considered pipe size, but it makes sense that a bigger highway allows more cars. I'm going to see if I can determine if my pipes are simply a smaller gauge. Does the size of the pipes connected to my backflow preventer necessarily have to match the rest of the system. My RPZ appears to have 1" openings; not sure about my neighbors. I wonder if our backflow preventers are both 1", then our underground systems are too.
    – B MC
    Oct 20, 2017 at 16:43
  • I know it's cliche, but bigger really is better. For residential systems I generally use 1" anti-siphon control valves, 1" PVC "mains", 3/4" PVC "branch mains", no 1/2" pipe at all. Unfortunately, unless you dig you can't really tell what someone has buried, and changing it is not easy. I have found that changing 3/4" anti-siphon valves for 1", regardless of pipe size, sometimes gives me a boost. As a note, a pro will always graph out a system and calculate exact GPM requirements before they install anything, then overbuild it. Oct 20, 2017 at 21:55
  • +1 for recognizing the significance of a slightly larger pipe size. They may also want to remove the backflow preventer and flush the system in case something is partially blocking the pipe.
    – Lee Sam
    Sep 25, 2018 at 18:21

I doubt seriously if you have a pressure reducer in your landscape sprinkler system. No need for that. They all run at full pressure. As to your specific problem, I bet that you have some kind of a blockage in the line that is restricting the flow. Take the new sprinkler head off and make sure that it is clear. Then turn on that zone for a minute to clear the line. Then making sure to keep debris out of the riser reconnect the head. Now try it.

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