Our 10-year-old house is on hill in the woods in the Santa Cruz Mountains of Northern California. Our water comes from our own well; we have a pressure tank that gives us enough water for irrigation. However, with extended power outages, we have seen pressure drop quite low in the house.

The foundation and retaining walls are well designed and recently inspected. We are working to stabilize the hill above the house with trees and bushes. We have excellent recommendations for species to plant from the local agricultural extension. We are planning a drip irrigation system.

My questions are, what sort of backflow prevention do I need to install on the irrigation system, and where do I install it? I assume I will run a 1" main irrigation line up to a valve manifold above the highest drip outlets. That line will be 50-75 feet long.

Thanks!

generally a sprinkler backflow device is place on a tee before the water meter to save on the sewer bill.
in your case there is no meter so you locate the device where it will do its job but be able to be serviced/replaced when the time comes.
since your sprinklers will be located up on a hill you will need a special 'below grade' device.
you might have a chat with your local inspector as to which device they want.

BTW... there is the possibility of running the feed for the sprinkler piping all the way to the highest point (at least 12 inches above any head) and locate a standard backflow there with ALL the heads being downhill of it.

[www.google.com]

Dave
I suggest a spill resistant vacuum breaker backflow device just remember to winterize the entire line that will be exposed to freezing conditions in the colder months

You could also use an atmospheric vacuum breaker both are testable

If you looking for something a little more user friendly a standard dual check valve can be used

NONE of those are approved for a system with heads ABOVE the BFP device.

Perhaps I misinterpreted the ops plan

He plans to run a 1” main up to a high point then install a backflow device, from there run piping to the heads or using an irrigation hose which are planned to be below the actual device in which case all of the fire mentioned devices will work

As a general rule in California a reduced pressure device (rpd) is required for irrigation.

It can be located above or below irrigation system.

Device should be tested once a year by a licensed tester.

Agreed but around here all testable devices and assemblies are required to be tested annually and results submitted to the water company not required by the township who’s minimum standard is just a non testable dual check valve

The op being on a well is not subject to any penalty by not testing in which case a non testable device can be installed

Rpzs are normally installed within the residence most outdoor testable devices are of a vacuum breaker type because they are easier to winterize

All that said having a testable device is better peace of mind as you know whether it is working or not

Unless there's a local amendment, this is the 2019 CA Plumbing Code section -

IF I understand correctly, that is what someone suggested, NOT What he originally planned to do.