Irrigation Backflow

[Carol]

I have an in-ground sprinkler system with a separate city water supply and meter for irrigation water. For anyone that doesn't know, irrigation water is a lot cheaper than house water because it doesn't go through the sewer and doesn't have to be treated. Theoretically, it is all consumed by grass and shrubs.

My problem is that I sometimes hand-water plants and flower beds but all of the spigots around the outside of my house are on the *house* water supply and meter, not the irrigation water supply. It would save me some money if I could use irrigation water. I would like to splice into the irrigation water supply - possibly through the backflow - so that I could connect hose and use the cheaper water for those purposes.

In Florida, most everyone with an irrigation system has an upside-down u-shaped set of PVC piping that comes up and back down to the ground where the backflow is located (I think). Can I have an irrigation specialist cut into that and add a spigot? Does anyone know if the city (mine happens to be Jacksonville) would have any problem with that? Could I do it myself? (I do know how to change sprinkler heads, add risers, etc, so I can be somewhat self-sufficient, when I need to.) How would I know which side of the valve to cut into and add? Also, just FYI, there is a shut-off valve at the street for the entire water supply.

Thanks! Carol

[isospin]

Better check your local city/town rules before doing this. I know where I live it is not legal to have any kind of spigot on the irrigation meter, only the sprinklers themselves.

For a backflow preventer to work properly, it needs to be higher than the highest sprinkler head (at least that is the kind used on most residential systems.) If you attach a hose, the hose end then becomes the sprinkler head, and there is now no guarantee that it will always be higher then the highest sprinkler head, and you can have backflow into the city water supply. If your backflow device is high enough that your hose end will never go above it, you are probably safe, but regardless case you may be violating plumbing code.

Anyway, all new heads (valves) must always go downstream of the backflow preventer. The backflow device must be between the main water supply and the irrigation valves.

Sundeep

[Carol]

You are right about the height of the backflow device currently being the highest point in the system. The backflow comes above the ground (and all ths sprinkler heads) about a foot. If I hooked up a hose, when I hold it in my hand, the hose would be higher much higher and I guess there could/would be backflow into the city supply. Darn gravity. Thanks very much for your help.

Carol

[Carol]

Just had another thought/question. Doesn't the backflow prevention device do just that?--prevent backflow? Only if it is the hightest point? I guess you said that. Just confirming.

Carol

[Carol]

In another forum, it was written, "Yep ... you can add a hose connection anywhere along your irrigation main downstream of the backflow ... if it's a big garden you could have a quick disconnect valve ( a hose connection in the ground )installed in a valve box out in the garden so you do not have to drag around hoses and the hose connection would be out of site when not in use."

A couple people mentioned a quick connect valve in the valve box. Are they all wrong? I still want to do this if it is possible. Thanks for any help or advice.

Carol

[zxcvbob]

I don't know what's legal where you live; you'll have to figure that out. Depending on the type of backflow preventor, it could be before or

*after* the irrigation valve. You really don't wanna mess with it. Tap into the supply line between the meter and the irrigation valve. The faucet doesn't need to be after the backflow preventor because it uses an air gap (or your local laws require you to have a vacuum break at the faucet itself.)

How much water are you talking about? I suspect the savings are a lot less than you think for the amount of water you'd use with a garden hose.

Best regards, Bob

[Carol]

That's a great idea. I have to figure out how to find the supply line

- I know where the meter is and I know where the valve box is, so I guess it is somewhere in between.

The cost differential is every gallon of house water costs four times more than a gallon of irrigation water.

Thanks for the help.

[isospin]

Carol, look at

It has a lot of useful sprinkler stuff. I am not affiliated with this site, just went there a lot while learning how to expand my home sprinkler system.

Most backflow preventers, save the most expensive commercial types, will not work against gravity.

The website does a good job of explaining how all this stuff works.

Sundeep

[Carol]

Bob,

This may be dumb question. If I understand it right and I tap in between the meter in the supply line, there would be no backflow prevention. Wouldn't the city have an issue with that? I just want to make sure I get this right the first time. Thanks for helping me. I really appreciate it.

Carol

[zxcvbob]

As long as the faucet is not at ground level you have an air gap between the faucet and ground water (or the bucket you put under it.) This may or may not be enough backflow prevention where you live. It should have the same regulations as the faucets on the house supply. Some jurisdictions make you use antisiphon faucets or install a vacuum break (to protect the water supply when you leave a hose attached to the faucet and have the end of the hose on the ground or in a bucket.)

Gary S. can probably give you advice with more details than I.

If they use "double check valves" where you live and if the check valve is before the irrigation valve, you can tie in between the check valve and the irrigation valve and get your backflow prevention that way. I don't know what your local regulations are and I can't see your current set-up from here. :-)

Also make sure you have a way to shut off and drain the lines if freezing is a problem where you live.

Best regards, Bob

Carol wrote:

[Carol]

Actually that was one of the first places I went. Unfortunately, he does not address this question anywhere that I could find. He will answer questions in exchange for donations. I may consider that if I can't gather enough information on my own. Thanks for the tip.

Carol

[Carol]

Just for anyone still following this thread: I talked with the licensed plumber who performs my annual (required) backflow prevention testing about installing this hose bib on the downstream side. He said it was no problem and was not a code violation. (He seemed very familiar with what I was asking - finished my original question for me.) So woo-hoo! I'll give it a go next weekend.

Carol

[Delirious_d]

Carol, it sounds like you have two water supplies to your house, correct me if I'm wrong, a potable water supply that supplies drinking quality water for household use, and another non-potable supply for irrigation purposes. If you have a backflow preventer, it is likely there to protect the potable water supply, meaning tapping into that line will not get you the cheaper low quality irrigation water you are after. Backflow preventers are installed to protect water quality in the public potable water supply, from the non-potable water quality in the irrigation supply. At any rate, the safety of people drinking the water in your house as well as your neighbors is at stake. You really should call your water department and ask someone before doing this. I am a water quality specialist in my state and take calls from time to time from people with similar questions, and believe me, they are frequently very glad they called. Don't take a chance, call.