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Thursday, July 13th 2017, 11:45pm

Making Sure I Understand RPZ...

Hello, I'm new here and after reading the forums and other online sources I want to make sure I understand the use of an RPZ correctly. I'm installing a new irrigation system for our new house where the highest sprinkler head is about 36" above our stub-outs, so a PVB isn't really feasible. We are located in Colorado.

I have space in the mechanical room in my basement where I can install an RPZ, so then I don't have to make room for it near the stub out, and I don't have to worry about it freezing. Here are my questions:

1) I'm planning to use a Febco 825Y. Is this an appropriate RPZ? Febco also makes an LF825Y which is lead-free. Do I need to use this instead? Or is that just for when the downstream system is potable water?

2) Any issue with putting it in my basement, which is below the entire irrigation system and about 10' below the highest sprinkler head?

3) I have floor drains in the mechanical room, so am not too concerned about occasionally expelling water. However, I don't want this area to always be wet, so does it just expel on rare occasions such as during blowout or a backflow condition? Or could water come out on a daily basis?

4) Should I instead consider a Double Check Valve Assembly? If so, why? And which one should I consider? My biggest issue with the RPZ is that it's about a 10 PSI drop at 10 GPM (1"), and the expelling water could become slightly annoying (although not too concerned about that).

Thanks so much!!!


Supreme Member

Posts: 5,135

Location: Metro NYC


Friday, July 14th 2017, 8:29am

You have to use a lead-free RPZ. Any brass backflow preventer connected to potable water has to be lead free nowadays, due to federal law.

As for your own system, as you described it, no big whoop exiting the basement with your copper and running it up 4+ feet to a PVB. You save money. You avoid maintenance issues with an RPZ. (You really, really, really don't want these things in basements) Every home built nowadays has an outdoor area next to the house with utility meters and probably air conditioning, so one added pipe is not going to be a big whoop.


New Member


Friday, July 14th 2017, 10:21pm

Thanks for your response. How come they still sell the 835Y since it's not lead-free - where would be the use case? The LF825Y seems to be a bit harder to find, that's really the only reason I ask.

We actually have two stub-outs (we are on 4 acres), one is near our deck and the other is on the front of the house; putting a PVB 4' above the ground would be aesthetically unacceptable. I'm curious, why do I really not want it in my basement? Do they expel a lot of water frequently? I called my building authority today and they said they don't care whether I use an RPZ or a double-check valve. I like the idea of the double-check because it doesn't expel water, doesn't cause as much pressure loss, and is smaller and cheaper. Any reason not do go with the double-check and put it in the basement? Thanks!

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