Since nobody has responded, you might want to ask this on the Irrigation or lawncare forum.

How do you turn it off for the winter? There should be a main irrigation valve somewhere for the entire irrigation system, back before this upside down "U".

Sometimes pressure can be reduced at that main valve.

If you don't have a main valve then you may risk freeze problems unless you are located down near the southwest corner somewhere.

The city turns off the pressurized irrigation in the winter and back on in the summer. I think it's off from about mid-October to mid-April or so. I've spoken with more neighbors and one seemed to think that I could reduce pressure for that zone by tightening a screw on the valve for that zone. I'll have to get back out there and start fiddling with things and see what happens...

Cycler, I'm having the same issues. I don't think turning down the screw on the sprinkler valve is an ultimate solution, because in my case the sprinkler valve is actually starting to leak. I have two valves that are emitting a small stream of water from the place where a big plastic screw can be turned to reduce the flow. I'm going to have to put in an inline pressure reducer before it goes to all the valves to be sure I don't damage any more valves.

In my case, it's easy to do this, because I installed my connection to the pressurized irrigation system. I ran a pipe up the side of my garage and attached it to the existing sprinkler system after cutting off the line that went to the culinary water. I'll just have to dig up a piece by the garage and put the pressure reducer in. I hope I can get the right balance of enough pressure to keep the sprinklers shooting as far as they need to go and enough reduction to protect from leaks.

I also hope I don't have any hidden leaks underground somewhere in a pipe joint. In the next few years, I expect my city to start metering the irrigation water, and I don't want to find out I'm using way too much (and have to pay way too much!) because of a leak I didn't know about.

I still need to experiment with the screw on the valve, but I just don't have any idea where I could put in a pressure reducer for the whole system. There are no markings for pressurized irrigation on the curb. I guess the next step would be to call the city or something. I posted a similar message on the irrigation forum and there's been only one response about installing a gate valve ahead of the offending sprinkler. I was looking for a more comprehensive approach...

On another note (still irrigation), my sprinkler timer has a mystery schedule. It is set for one day a week, Sunday morning, to cycle through each station at three different start times (the last one at 7:30am), but it is usually still going around noon. I probably need to make sure that the run time per station doesn't cause it to overlap with the next start time. The other mystery is the Tuesday start. I've unplugged the unit and reset all of the watering times and schedules, but it still starts up on Tuesday mornings even when there is no schedule to run them on Tuesdays. That one baffles me, but I guess twice a week isn't bad compared to my neighbor or the park that seems to go every morning and evening.

I would think you have an inline filter installed somewhere on your irrigation line before it enters your sprinkler system. Cedar Hills makes us install one before we're approved to use the pressurized irrigation system. Are there any in-ground boxes like your valve boxes in any other place in your yard? Near the sidewalk or on the side of the garage or something? It's likely to be somewhere between one of your valve boxes and the nearest sidewalk. If you could find that, you could dig near it and put the pressure reducer in before or after the filter unit.

A pressure regulator should be installed. The screw on the top of the valve body or the valve body handle (electric valves) is a flow control. It will not reduce pressure. You need either a watts regulator or a fixed pressure reducer like Rainbird makes to solve your problem. Most sprinklers are only rated to about 50psi. 30-40 psi is about perfect. The regulator should be placed ahead of the valves.

Thanks for all of the responses. I've finally found it! My neighbor on one side showed me where his shutoff valve was, then I noticed that there were two "PI"s scratched into the curb, so I went wading through all the growth in that area and found it in the middle of a side bed about ten feet in! It's a tiny circle instead of the rectangular box, right underneath what I believe is some type of willow shrub, from what I hear. I guess that's a different topic. At any rate, it will be a real challenge to work under there with all the growth - overgrowth. I'm not quite sure whether I will dig up most of the line to install a filter and pressure reducer, or if there's even enough room. At any rate, I better hurry, or the water will be shut off before I can test it out!

Speaking of which, my utilities from the city (water, sewer, garbage) jumped up about $20! It had been exactly the same for over two years, with an occasional reading of how much water we used, although it wasn't clear whether it was just culinary or included pressurized irrigation... No notice of the change, either.

Glad to hear you found it. Hey, my water rates went up about $20, too. Darn cities.

Anyway, you should know that the Central Utah Water Conservancy District is giving 50% rebates on specific types of irrigation products you buy before October 15. Read about it here. The actual form (PDF) is here.

I still haven't bought my pressure reducer, but I need to do it and get the rebate.

Check it out, here it is, completely hidden way under something... any clue what it's called? I cut it way back in early spring and now it's bigger than it was last year! I've also figured out Picasa. Talk about making things simple for you!