Backflow valve or anti-siphon; or refigure.

[John N.]

I have a situation I hope I can find some help with. I have asked a couple of times before on your forum and the answers given were a great representation of the talent that lies here. I am doing an irrigation system on my home that was recently built. I am going to supply irrigation water to about an acre of land. I have a 1-½ main that runs about 200' from the roadway to the house. About 75' from the roadway the builder put a tee up from the main to use for water supply for irrigation. From the street to the house is about a 25' rise in elevation. So where my tee comes up for water supply, it will tee water off in two directions, and feed off to supply water both up hill, and down hill. I have trenched and laid about 500 feet of 1" supply lines from the tee, but have not connected to the tee yet. I plan to use in-ground valves and have a diagram which utilizes a twelve station plan. It was done by the pipe supply store off my landscape plans and did not take into consideration the rise in elevation from the supply point and showed the irrigation supply at the house entry point. What isn't in the plan is what kind of backflow device to use where the water supply tees off of the main at the 75' point from the roadway. I didn't want a bunch of anti-siphon valves above ground next to the garage where the main attaches to the house, thus the want for in-ground valves.

So, do I have to put some kind of anti-siphon valve at each in-ground valve, at every station, or can I get by with some kind of backflow restrictor at the two sources where the irrigation water supply tee leaves the main. And, if the backflow restrictor is at the two places the water supply leaves the main, will that allow water flow both up hill and down hill? I will probably seek some installation assistance from a professional, but would like to know what my options could be beforehand. Or, maybe my whole idea is assbackward; but I got pipe laying in trenches, so I hope it's workable. Sorry about the rambling, but I wanted to try to give a complete picture.

Thanks so much for your time to read and advise.

JN

 

[99k]

I'm not an irregation guy but in my area you need the highest form of protection which is an RPZ valve (very expensive and should be tested annually) to prevent crossed connection and have irregation water and pesticides backflow into the water supply. I believe you need it at the first tee but it must be accessible.

 

[Sponsor]

 

[Wet_Boots]

Location location location - need it to supply the correct answer. An RPZ device will cover all backflow possibilities, at a cost of a few hundred, and a pressure loss of 10 to 15 psi.

 

[99k]

I have a situation I hope I can find some help with. I have asked a couple of times before on your forum and the answers given were a great representation of the talent that lies here. I am doing an irrigation system on my home that was recently built. I am going to supply irrigation water to about an acre of land. I have a 1 ½†main that runs about 200’ from the roadway to the house. About 75’ from the roadway the builder put a tee up from the main to use for water supply for irrigation. From the street to the house is about a 25’ rise in elevation. So where my tee comes up for water supply, it will tee water off in two directions, and feed off to supply water both up hill, and down hill. I have trenched and laid about 500 feet of 1†supply lines from the tee, but have not connected to the tee yet. I plan to use in-ground valves and have a diagram which utilizes a twelve station plan. It was done by the pipe supply store off my landscape plans and did not take into consideration the rise in elevation from the supply point and showed the irrigation supply at the house entry point. What isn’t in the plan is what kind of backflow device to use where the water supply tees off of the main at the 75’ point from the roadway. I didn’t want a bunch of anti-siphon valves above ground next to the garage where the main attaches to the house, thus the want for in-ground valves.

So, do I have to put some kind of anti-siphon valve at each in-ground valve, at every station, or can I get by with some kind of backflow restrictor at the two sources where the irrigation water supply tee leaves the main. And, if the backflow restrictor is at the two places the water supply leaves the main, will that allow water flow both up hill and down hill? I will probably seek some installation assistance from a professional, but would like to know what my options could be beforehand. Or, maybe my whole idea is assbackward; but I got pipe laying in trenches, so I hope it’s workable. Sorry about the rambling, but I wanted to try to give a complete picture.

Thanks so much for your time to read and advise.

JN

Will you be injecting any kind of chemicals into the irregation system?

 

[Masterpumpman]

City/State Regulator Requirement?

If this system is being supplied water from other than your own private well I would recommend that you contact your water supply engineers to see what they require in a back flow preventer. Water Suppliers usually have their own preference of approved back flow valves and many valves may not fit their requirements.

 

[Gary Swart]

Regardless of whether your city or state requires or enforces a back flow preventer in an irrigation system that is connected to a domestic water source, why would you risk your health, your family's health, and everyone else's health that is on your water supply main? All it would take is for an animal to take a dump on one of your sprinklers and your household water and the city water main could be contaminated. What you need is a back flow preventer on the irrigation side of the tee and before the first sprinkler. A system this size should have a serious double check preventer...and yeah, they ain't cheap! Moreover, this preventer needs to be checked annually by a certified inspector to verify that it is still functioning properly...they will begin to leak back after several years. If you are pulling water from a well, all of the above applies except the possible contamination of the city supply.

 

[hj]

bfp

Any common backflow/vacuum breaker device would have to located at least 12" higher than the highest head in your system which might be inappropriate if the system is going uphill from the connection. In this case you probably need a RPPBFP device regardless of the minimum requirements in your area. Even individual valves with vacuum breakers would have to be 12" above the ground which would also be unsightly.

 

[Gary Swart]

I believe HJ's reply is somewhat misleading. There are back flow devices that can be in a box below ground and sprinkler level. They must be accessible for testing as I described in my earlier post and they are expensive, but fortunately they do not require frequent repairs and the repair parts are not too expensive.

 

[John N.]

Thank for the info

1. Gary - I'm not going to risk my health, my family's health, and everyone else's health. That's one of the reasons I am trying to get some information on the right system to install.

2. I am not on a well, I am on city water, but in foothills of the Sierra Nevada Mountains in northern California.

3. I am not going to use any chemicals introduced into the system.

4. If the only option is to use a couple of RPPBFP devices that set me back a couple of thousand dollars, maybe I should use that money and have everything retrenched and come off where the main enters the house. Ex-city boy used to working on things on a flat 150' x 50' lot. Guess it's time to go back to the drawing board and take my original posted option 3; refigure.....

Thank you all for your input and assistance.

JN

 

[Gary Swart]

WOW! I don't know where you get the idea that a backflow preventer will cost thousands of dollars! A 1" double check valve will cost in the neighborhood of $100 to $120. I would urge you to do a Google search on the topic.

I have been told that in Yakima, Washington where I live there are thousands of connections that require a backflow prevention device. When a homeowner first installs an irrigation system that tees off of his domestic water supply, the city's Cross Contamination Division of the water department makes the first inspection. In the spring of each year after that, the city mails a list of certified private inspectors to everyone with a backflow device. We are required to have one of these inspectors test our device, and repair it if necessary. If we fail to comply, the city can and will shut our water supply off until we are in compliance. Since you are in California, I would be quite amazed if there are not similar requirements of a backflow prevention device. It's really not such a big deal, I have had my irrigation system in operation for 24 seasons. I had one preventer freeze and break (my fault) and the second one which I remove and store inside in the winter, had to be rebuilt this spring at a cost of $30.

 

[hj]

backflow

Gary. A "backflow" device CAN be installed underground, but irrigations systems MUST be protected by a combination backflow/vacuum breaker, and THAT ALWAYS has to be above ground, specically 12" above the ground, AND/OR 12", (whichever is highest), above the highest head outlet unless it is an RPPBFP device.

 

[Gary Swart]

I may have erred in my terminology, and be talking about apples when you are talking about oranges. This is the device I use in my system except mine is a 1" unit. It is located in a box that is just below ground level and at least half of the sprinklers in the system are either at or above this level. It has passed city inspections and more recently independent certified inspectors every year for the past 24 years. Sorry the photo didn't appear to copy, but a quick Google search on "Wilkins 950 will provide a photo.

Wilkins 950XL Double Check Back Flow Preventers

APPLICATION

Designed for installation on potable water lines to protect against both backsiphonage and backpressure of polluted water into the potable water supply. Cap is provided to protect against fouling caused by insects, dirt and debris. Assembly shall provide protection where potential non-health hazard exists. Used In many Cities for an approved Back Flow for Sprinkler Systems. Always Check City Codes For New Installations.

ASSE® Listed 1015 (Vertical flow-up:1 1/4" thru 2" IAPMO® Listed AWWA Compliant C510 CSA® Certified

(Vertical flow-up:1 1/2" & 2")

Approved by the Foundation for Cross Connection Control and Hydraulic Research at the University Southern California

SprinklerSupplies4Less.com Wilkins950XL.jpg

Wilkins 950 Double Check Back flow Preventers

Wilkins 950XL 3/4" $99.29

 

[hj]

valve

Quote;
Assembly shall provide protection where potential non-health hazard exists.

That is the reason it is not approved here. There IS a potential health hazard.

It does not have an atmospheric vent, and if it did have one it would have to be elevated to prevent submersion or fouling by debris. That one says it has a cap to prevent fouling but does not address immersion. Even the normally minimum standard "pressure vacuum breaker" is not universally accepted here. Some cities require the most stringent standard, an RPPBFP valve, for all irrigation systems regardless of their configuration.

 

[Gary Swart]

John N. Check your private mail.