Backflow Prevention: It’s Spot in Your Irrigation System

Working irrigation repairs is often like solving a puzzle. Sometimes that puzzle is like the children’s jigsaw, fitting 10 pieces together to create a cohesive picture. Other times it’s more like 500 pieces, and you end up catching yourself staring at all the parts, scratching your head. But no matter the size of your puzzle, some pieces stick out more than others. For me it was always the 4 corner pieces, and just like a jigsaw, your irrigation system has 4 corners too. These “cornerstones”, if you will, are as follows; a stop and waste, backflow, manifold, and an irrigation clock. On our previous blog, we went through “Backflow Prevention 101”, or basically why a back flow is important. Within this week’s post, I want to continue this line of thought by delving into where an outdoor backflow is in your system. That way you will know where to look, and what to do if you need to quickly turn off the water to your irrigation.

Finding a simplified diagram of a backflow layout was near on impossible, so we get a hand drawn one instead. …Bear with me…

So, at a quick glance you can see that I have circled 3 out of our 4 irrigation “cornerstones”.

1. Stop and Waste
2. 720A Backflow (Wilkins)
3. Manifold (Valve Box)

I have specified a Wilkens 720A for our backflow preventer because in a residential setting, this model is the best bang for your buck. Plus, it is unrivaled in regards to easy install and repairs (In my personal opinion). Although there is a wide range of options when it comes to picking out what brand or model you want, this is the one that I will always refer to. Sooooo… Let’s get back at it.

If your system is plugged into an outside, shared water source, finding your backflow should be pretty easy. Water for your system is usually diverted from your home’s main waterline, by a stop and waste. (If you have no idea what a stop and waste is, that’s okay. Check out https://lookslikerain.store/blogs/news/stop-and-wastes-what-the-heck-are-they)

For the purpose of this blog, here is all you need to know about stop and wastes. Most systems will have 2 on/off valves, usually located near each other. One controls the water flow to your home (a curb stop) and the other controls the water to your irrigation system (a stop and waste). More times than not, your home’s curb stop is located close to a side walk, road, or the end of a driveway. Whereas the stop and waste in control of your irrigation system, will always be adjacent and somewhere behind the main one. (The picture to your upper left is a diagram that gives an idea of what this looks like.) Understanding which ball valve is in relation to your irrigation important because 80% (this is not a proven figure …it’s just based on my personal experience) of the time your backflow preventer will be located on the same side of your home as your stop and waste.

Based on our first diagram, we know that a backflow is the 2^nd “cornerstone” in our irrigation line up. So, by following the flow of water we will find our backflow’s location. …If your very lucky, the stop and waste and backflow will be side by side. If you’re not one of the lucky ones, look for a copper and brass apparatus that sticks up at least a foot from the ground.

Knowing where your backflow is important for a few reasons.

1. If there is a break in your system’s lines, OR water needs to be shut off to your system due to repairs further down your system, the backflow is the fool proof, and easiest way to do so.
2. Although it is not required to test functionality of residential backflows, it is recommended to do so every couple of years. Doing so ensures it is working as it should to prevent backflow contamination into potable water sources. This is done by a licensed irrigation technician. However, knowledge of the backflow’s location, for this test is important …obviously.
3. Backflows are the best way to flush out an irrigation system. This comes into play heavily when winterizing your system.

So to finish this blog, let’s swing back to reason #1 and quickly discuss how to shut off water to your backflow.

As you can see in Figure A, the handles on our ball valves are in alignment with the valves, meaning the backflow is open on both sides, allowing water to flow though. Whereas Figure B shows the handles being perpendicular to the valves, which stops all flow of water. When stopping water to your system, simply turn the bottom valve off (you can definitely turn off both, but it is not necessary). The reason your bottom valve needs to be turned off first, compared to the top valve is to eliminate unwanted pressure withing the actual backflow.

Understanding how an irrigation system works can be a real head scratcher, but by breaking the system into to smaller segments, the pieces of the puzzle come together to form a more cohesive picture. Backflows are a HUGE component of that bigger picture, and grasping what it’s purpose is, in your system will help you form that “bigger picture”.