Need Help please! changing from indexing to standard valve

I have an indexing valve and have already installed the Rachio 3 but now want to convert to standard valve so I can take more advantage of zone flexibility.

I have looked up some videos on how to do this and what parts I need but I still have a few questions.

  1. Whats the difference between an antisiphon valve and a backflow preventer? I know my current system has some sort of valve before the indexing valve but not sure what exactly it is. I want to replace that valve as it is old and seems to be leaking but Im not sure what I should get and NOT sure if I still need that part when I switch to a standard system (although I assume I still need it). My system runs on city water so I’m pretty sure I don’t need a pump relay box…

  2. Is it worth while to install the wireless flow meter? I purchased it a while ago and never got around to installing it. I can’t return it at this point BUT Ive been hearing very mixed reviews about its benefits. And I don’t want to spend the extra time installing it if its not going to be for much gain…thoughts?

Thanks so much for any assistance you can offer!!

Katie W.

  1. Both valves have the same basic function, to protect the potable water system from contamination from the sprinkler system. Antisiphon need to be installed higher than the highes sprinkler or drip emitter to be effective. This means you will have a number of valves plumbed up in the air, one for each zone. I personally don’t care for antisiphon valves because each time a zone turns of, by design, the pressure is bled off and water is dumped out of the valve onto the ground.
    A backflow preventer is a (usually brass) device that would come off thr main water line, be plumbed at the highest point, and from there, standard solenoid valves would be installed at ground level, or vetter yet, underground in an irrigarion box. No water should ever drip from these unless there is a crack in the bonnet. This is my preferred method if you are redoing the system.

  2. if you have it, and are re-plumbing the system, it wouldn’t be a bad idea to install. Rachio will not discontinue the use of the flow meter via software, and the leak detection could be beneficial.

Ok thanks. I’ll purchase a brass backflow preventer… but don’t the individual valves each have their own solenoid component? (I think that’s what you are implying but I’m new to all this so want to make sure I’m not misunderstanding) I don’t have do a separate solenoid component right?

Thanks again!

There are a number of different manufacturers and they will all look a little different, but function the same.

I personally like the Hunter PVG valves. This is what they look like. The solenoid that you wire up to Rachio is the two red wires on top.

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I already purchased 4 orbit valves… hopefully they’ll be fine…

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Should be good! Those downstream of a backflow preventer, and you should be good. With some creative piping, you should be able to use your underground piping after removing the indexing valve.

Ok perfect! Thanks so much!

I’ll let you know if I have any issues

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Ok so I’m at Home Depot and I was wondering does it matter to join brass to pvc? As my current stuff is pvc but you say most backflow preventers are brass…

I have found pvc options and brass options…I assume I need a construct similar to this. (But with the appropriate size pipes as I just grabbed something to take a pic)… do I need a valve on both sides of the middle check valve piece???

I was thinking of just using pvc and glueing it together if possible… although some of the pvc valves I found are threaded so not sure which is a better option…


Forget to send the pic… here it is


What you have in that picture is a check valve. Similar concept, but not the same as a backflow device. You’ll need to find something that looks like this. This is a Zurn brand, Home Deopt I think stocks Wilkins, but they look similar.

As for connections, if staying PVC, you will just need some PVC male adapters to screw into each end of the backflow.

Ok I’ll look for that… so it is ok to screw pvc into brass? I wasn’t sure if you needed a special adapter

And I assume if I’m using the brass backflow you are showing and you pvc male adapters (I assume I don’t need a rubber washer or anything?) then I would use a 90degree elbow to take the pvc pipe down back to the ground to the new individual valves…??? Sound correct?

I’m on my way back to Home Depot anyway be I didn’t realize the individual valves I bought had threaded female ends so I have to go find what I need for each end on those… if you know of the top of you head what I need let me know… thanks!

Totally fine. Best practice is to screw a male PVC into female brass (just make sure to use some Teflon tape). Other way around can lead to a cracked PVC fitting and failure.

Is there a specific name for the backflow preventer so they can help me find it

Sounds about right. Here is how my backflow is plumbed off the water main coming into my house. I just recently had it re-piped so the main shut off to my house was plumbed AFTER the irrigation system. Mine is plumbed in and out of the backflow with copper, and transitions to PVC underground somewhere, but the concept is the same.

What are you using these valves for? The backflow device will have a valve on the inlet and outlet already. If for another use, exchange them for glue type, they should have them.

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Well now I’m not sure I need a backflow preventer as the people at Home Depot say that since my sprinklers run off city water you don’t need that preventer by there’s already so much pressure in the line… they say that you only need that if you run off a well or canal…

The other valves I was speaking about are the individual valves for each zone… i didn’t realize they were threaded and obviously my sprinkler pipes are smooth so I need a connected for that

The pic on the directions shows some connector pieces attached… I just have to find them


Gotta love Home Depot experts…Running off city water is exactly why you’d need one. It’s code in most areas so that you don’t backfeed the city water system with contaminated water in the event of a pressure loss on the city side.

Here is one of my valve boxes in my yard. These valves run the grass zones in my front yard.

Keep in mind the valves you ordered are threaded as well, so you will still need some male adapters to connect. The valves are 1", and chances are, your piping is 3/4, so you will need a 1" male thread x 3/4 glue adapter. You’ll also want to get some waterproof wire nuts to connect all the wiring together.

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Ok well I picked up 4 of the hunter valves you like since 2 of the 4 orbit ones I bought on amazon were cracked… I got the adapters for it… so should be good there…


As far as the backflow valve goes… these guys say they’ve never seen it… I’m gonna have to look harder in the plumbing section to find it… otherwise I guess I could order it on amazon but wanted to get this done this weekend… :woman_shrugging:

***and I assume in the pic you showed- the painted pipe that comes of at a 90 degree angle is the one that goes back to the sprinklers… the copper one coming from the ground is from the main line from city???

For the male adapters, just make sure the size of the glue end matches what you have in your current system that you are tying in to. The picture looks like a straight 1" male adapter, but most likely you will need a reducing male to get it down to 3/4, but I dont know for sure what you have in place after your current indexing valve.

In my picture, you are correct on the piping. Line on right coming out if the ground is the city main. Left, after the backflow is the line going to the various valves around my yard.

As for the backflow, they should have it. I’ve not seen a Home Depot without them…