What backflow would you recommend?

post by giuliano on Aug 26, 2019

Good day,

I would like to know what backflow would you guys recommend to use. I am having a hard time to find one at my local Home Depot or Lowes here in California and the reps do not have any clue why I am trying to do and they say there is no need for it if the sprinkler valves have anti-siphon.

Also, I want to mention that my house has a charcoal filter and water softener that is connected to the water main line. The irrigation water is just a T before the water goes into the house.

Thanks in advance.

post by tmcgahey on Aug 26, 2019

Well, if your current sprinkler valves are the Anti-siphon variety, a backflow device isn’t needed. Do you know if you have anti-siphon sprinkler valves, or regular?

Anti-Siphon:

Standard Valve:

If you decide you need a backflow device, do you need pressure reducing built into it?

If not:

https://www.homedepot.com/p/Wilkins-1-2-in-Brass-Pressure-Vacuum-Breaker-12-720A/203448602?MERCH=REC-

If so:

https://www.homedepot.com/p/Zurn-3-4-in-Brass-Reduced-Pressure-Principle-Backflow-Preventer-34-975XL2S/304957724

post by giuliano on Aug 27, 2019

Thank you so much, yes, I have the Rain Bird valves with Anti-Siphon below:

https://www.homedepot.com/p/Rain-Bird-3-4-in-Anti-Siphon-Irrigation-Valve-with-Flow-Control-DASASVF075/100036021

One more question, do you think I need the expensive backflow preventer (what a difference in price) if I have these 25 lbs pressure regulators on the output of each irrigation valve?

https://www.homedepot.com/p/DIG-25-psi-Filter-Pressure-Regulator-with-3-4-in-Pipe-Thread-D54/204758564

post by tmcgahey on Aug 28, 2019

No, you should be fine. As long as your anti-siphon valves are installed above ground and higher than any sprinkler or drip emitter in the system, you should be fine without a backflow device. And those pressure reducers are typically only installed for drip lines, but they aren’t going to hurt anything on a sprinkler zone…

post by giuliano on Aug 28, 2019

Thanks a lot. Very helpful information.

post by stupdcat on Aug 28, 2019

You may want to check with your local water supplier. They may give you direction as regards backflow prevention. My water district REQUIRES a backflow device.

Also, check out https://fccchr.usc.edu/list.html; USC has more info than you can imagine on this topic and a list of approved devices.

post by neilhunt on Aug 29, 2019

Clarification: even if your valves have backflow preventers, if you have a hilly landscape and the backflow preventers are not higher than the sprayers/drippers, you still might want to have a central backflow preventer (because gravity back pressure can keep the BFP from venting). A dedicated BFP has forward and backward pressure release. Mostly an issue if you are using manure or chemicals on the irrigated landscape - since you don’t want that re-entering your house or city drinking water.

Also, I find the integrated BFPs always leak within a few months, which is not great. I prefer a central BFP and simple valves with no BFP.

Amazon has BFPs like this: https://smile.amazon.com/gp/product/B0012QGSKC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1.

BEWARE that many vendors including Amazon still sell parts like this that have lead in the brass fittings. California (which it sounds like you are in) REQUIRES lead-free devices. The link above is for a lead-free BFP. If in doubt, make sure it is listed for DRINKING WATER.