SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Just an FYI to the people that run this site... I only just now got a notification that someone replied to this thread (I did NOT get a notification back in early July when they apparently did reply to the thread). The email headers suggest it was just sent now.

The choice of contractors installing toxic-rated backflow protection is the PVB, located at a height that is at least a foot above anything downstream of it. It would be worth the expense to install, because even a humble single-family home can become the target of a "backflow event", and a PVB at the correct elevation is trustworthy protection. It works on gravity, and gravity is generally considered to be in good working order at all times. I like the Wilkins 720, for its durable construction.

I respect both sides of this argument.
If I am the only one in the city practicing safe water protection, what is the point. This is a system fail.
For good information and pictures of why backflow devices fail.www.backflowinformation.com

I appreciate that you already have done substantial research.

The frustrating part for me is that in one region irrigation backflow can be a low hazard device (double check below grade).
In other regions it must be a high hazard device (PVB or RP).

I am happy to be involved in the water quality field. I began my adventure as a Sprinkler Contractor.

Playing the odds is something the various US regional plumbing codes have dispensed with, and they are correct to do so. Those codes basically declare the entire outdoors to be toxic, and require that it has no possible avenue of entry into a potable water supply. Since toxic backflow is prevented only by those devices rated to do so, that disallows a "dual check" device to serve as sprinkler system backflow protection, as it is rated as effective only against non-toxic backflow.

This "toxic backflow" designation might seem extreme to some people, but employing it creates genuine water-supply protection, and does so in a way that does not require constant vigilance, while also making it possible to confirm that the devices operate correctly (the "dual check" is a piece of brass with a label stuck on it, and you have absolutely no idea whether it functions or not - rest assured the manufacturers did not guarantee it would work perfectly forever and ever)

Well, while we're still on this topic...

I appreciate your advice about tightening regs down the road, but I think I'll just deal with it at that time if it ever comes. Unless I'm missing something, I see really zero sense in my using "proper" backflow protection if I know for a fact that nobody else using the system has it. Why spend that money if it is vastly more likely the contamination will come from someone else?

I fully understand that the United States has determined this device is insufficient for the purpose of backflow prevention, but at the same time 100% of the communities in my region of Canada (at least those which publish regulations online) either accept, recommend, or require the use of a dual check valve for "residential irrigation". To date, I don't know of any events of contamination ever happening. Unfortunately, I think that means they're taking the "well let's stick our heads in the sand until it happens" approach, which is just stupid. But it is what it is. What is really stupid is that there's no definition of "residential irrigation". Surely a homeowner could figure it might be a good idea to put a fertilizer injection system on their "residential irrigation" line, right? And the code makes no mention of a higher standard of backflow for this situation, but clearly it would be a bad idea to depend on a dual check valve in that situation. And they know this because when I spoke with the city engineer, she did as me "you're not intending to fertilize with your system are you?". But what if I was and it didn't occur to me to do all this research? I mean, it would be perfectly reasonable to expect a home owner to see the "dual check valve for residential irrigation" and not look into it any further.

The whole thing kinda makes me sick... figuratively speaking (hopefully I don't get sick literally from it down the road).

You could just install one of the "elevation proof" RPZ devices and forget to tell the town you did it.

Surely you can't think its a good idea to promote your business through blatant spamming? It is obvious that an enclosure isn't a "solution" in this discussion at all. Actually, an enclosure can't be a "solution" for backflow. Are you suggesting that by putting your enclosure on my property prevents backflow? Gee, that was easy.

Post reported. Good luck getting customers with this kind of behavior.

The solution for backflow is only the backflow prevention cage. We provide custom backflow cages with the safety issues as using by rounded edges. Provides extra durability and security in affordable price.
Contact us and let us know what your backflow preventers dimensions are and we will get to work on your custom cage.
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Your statements are consistent with other guides I've read. I find it pretty strange they would have such lax codes in an area where, supposedly, we have the highest quality drinking water in the world. We also have frequent fires to contend with (I know most people hear "Canada" and think snow, but here in the Okanagan Valley, we're actually in Canada's only desert. It is hot and dry here for 8 months of the year). Higher probability of hydrant use + higher than most irrigation frequency = higher probability of back siphonage. You'd expect the codes here to be higher than most, not more lax!

Unless... unless its all part of the overall plan and they handle it on a larger scale at the street level? Not that this helps our own home's water, but it might explain why they're not too concerned about it on a larger scale. She flat out told me NOBODY other than commercial and some much larger older lots use anything other than dual check valves for irrigation.

And it is specifically for the irrigation. It is clearly on that branch line after the meter and AFTER the TEE that goes irrigation/home.


Anyway, I'll investigate the anti-siphon valves. I'm not sure how I'd manage it with our terrain and winter conditions but I'll look carefully at it.

Thanks.

Almost nowhere in the United States would such a backflow preventer be accepted for lawn sprinkler plumbing. Its common usage is for whole-house protection, often installed right next to the water meter, as a sort of just-in-case safety measure.

The problem with lax codes, is that they can get tightened up later on, and paint a sprinkler system into a corner, needing pressure it doesn't have, in order to overcome the losses from added backflow protection.

You might take a lead from the device-inspection cost that was mentioned to you, and try to design with antisyphon valves. If you properly locate them higher in elevation than the zones they feed, you will have full toxic-rated backflow protection, and not have any inspection fees, since there isn't any way to hook a testing kit to an antisyphon valve. I would recommend an Irritrol 2711APR antisyphon valve, as something you can be sure will be serviceable in future years.