Backflow Prevention: What’s that about?
Posted by Emilie Zahurones on
Irrigation design can range from residential, and commercial, to agricultural. But no matter the scale or purpose, if water for your system is being pulled from a shared water source, a backflow preventor is a must. Without it, the potential and risk of contaminating a shared water source is increased. The American Backflow Prevention Association (ABPA) states that drinking water contamination due to backflow malfunctions are often not reported to the general public. However, it is estimated that more than 100,000 incidents happen within the United States a DAY. With numbers like that, owning or maintaining an irrigation system means that understanding the basics of backflow prevention becomes pertinent in guaranteeing shared water safety. As the ABPA states, “Not every incident [of water contamination] results in illness, but every incident poses a threat.”
Understanding the basics of backflow prevention means grasping the terminology. Now, the goal is not to go 8 layers deep with terminology. This is more of a beginner’s course, a 101 if you will. So, let’s start from the ground up.
What is a backflow Preventer?
A backflow preventer is a set of valves that prevent water from “upstream” of an irrigation system flowing back into the (shared) water source it is siphoning water from.
What does a shared water source entail? And what is backflow?
All irrigation systems siphon a portion of water off of a larger water source. These sources can vary depending on the size and purpose of the irrigation system. Shared water sources can be more natural, such as a well, stream, or pond. But they can also have a more municipal origin, such as a city water main.
So as the first image depicts: backsiphonage occurs when a break in the main water line causes a pressure shift in the irrigation system, causing the water to flow backwards towards the shared water source.
Whereas, backpressure happens when pressure within the irrigation system is greater than that of the shared water source. This can occur with systems that are gaining a large amount of elevation in a short amount of time OR from thermal expansion caused by heat to exposed pipes.
Backflow occurs when there is a reversal of water flow from a potential source of contamination into a potable water system or source. There are two types of backflow occurrences; backsiphonage and backpressure. Now I’m not going to go into depth about them since it would fall into “8 layers deep” terminology that I am trying to avoid.What is the difference between backflow prevention assembly and a device?
Yes, there are two kinds of backflows and yes, they are different. So, lets simplify the differences. Backflow Prevention Assemblies (BPA) include shut off valves and test cocks that allows for testing of functionality, and for winterization during off season. Whereas, Backflow Prevention Devices (BPD) do not have either of these features and work strictly to prevent backflow into a shared water source. BSA’s are what is used in irrigation systems.
What is a Shut Off Valve and Test Cock?
As previously mentioned, both these features are used to test functionality and are integral for proper winterization of an irrigation system. Most BSA’s will have at least 2 of each feature.
A shut off valve functions pretty much as it states; as a shut off for water either“downstream” to an irrigation system, or “upstream” towards a shared water source. Its very useful for flushing out water from the system, and to help with irrigation repairs.
The purpose of a test cock is to create an opening for testing and releasing water pressure, and as a port that allows air to flush out water during winterization.
So, what’s the take away for backflow prevention? If your lucky, you will never experience a backflow contamination to your drinking water. But why risk it? If you have an irrigation system, you should have a backflow. Shared water sources are just that, shared. Keeping your system up to date and functioning correctly is a must when maintaining an irrigation system, not only for your own health but for those who share your water source too.
Share this post
- 0 comments
- Tags: Backflows