Backflow Prevention Devices – Why They Exist And Why You May Need To Install One

Apr 20, 2020 | Agriculture, Commercial Landscapes, Domestic Gardens

Backflow Prevention Devices – Why they exist and why you may need to install one

Why do I need a backflow prevention device on my irrigation system?

Because they can save lives and it is in many cases is a legal requirement

95% of the landscape irrigation systems we install or design require a backflow prevention device. So there is a good chance you need one on your irrigation system

Basically many of the commercially available backflow prevention devices contain one-way valves, which only allow the water to travel in one direction. This means that if nasty contaminants enter the water through the irrigation system, your drinking water supply is protected from those contaminants.

When installing a backflow prevention device you need to consider a few things, including:

1.   Hazard Levels

2.   Pressure Loss

3.   Where the backflow device is placed

What Are Hazard Levels?

  • Low Hazard – domestic situation, hooked up to the drinking supply and has nothing fancy. We install a Untestable Dual Check Valve Device.
  • Medium Hazard – generally used on a commercial project, hooked into a drinking water supply. We install a Testable Double Check Valve Device.
  • High Hazard – usually on a commercial project where an alternate water supply exists or some form of chemical injection into the irrigation system is required (fertilisers, chlorine, treflan or another chemical). We install an air gap (which is a method rather than a device) or a RPZ reduced pressure zone device

 

How does the pressure loss through a backflow device affect irrigation systems?

Pressure loss through the backflow prevention device is not so much an issue with things like drinking fountains, baths, showers or even garden hoses; the water pressure would have to be extremely low for anyone to complain about these sorts of situations.

With pressurised irrigations systems, there is a minimum pressure required to run the emitters, for dripline it’s a much lower pressure, it could be anywhere from 80 – 150 kPa, but for a sprinkler, at the head, you need around 280 – 350 kPa or even more. Irrigation wont work without the right pressure to the outlets

Every fitting, valve or bit of pipe in an irrigation system will cause some form of pressure loss, Backflow prevention devices cause a significant amount of pressure loss. This needs to be considered in the irrigation design.

 

Where is the backflow prevention device placed?

Individual or Zone Device – the one that protects the water supply within the property is installed at the point of connection to the irrigation system

Containment Protection Device – Placed directly downstream of the water meter, to protect the rest of the water network(Public or town).

Frequent searches leading to this post: backflow prevention devices | backflow prevention melbourne | backflow prevention servicing melbourne | what is a backflow prevention device used for | sprinkler system backflow

 

Other articles that may be of interest

Need more information?

Call Ecostream Now!

(03) 5975 9898

Get a Quick Quote

What Tools Does An Irrigation Installer Use?

What Tools Does An Irrigation Installer Use?

What tools does an irrigation installer use? The tools to install a DIY irrigation system are available from most good hardware stores . But as projects get more complex we may use specialist tools that are more expensive and more difficult to find. At Ecostream we...

Do Irrigation Designers Need To Be Certified?

Do Irrigation Designers Need To Be Certified?

Does an irrigation designer have to be certified? No, But we choose to be  (using the term “we” loosely) Richard Jolly is our in-house Certified Irrigation Designer (CID) - And he is a gun, one of those guys that can do the theoretical and practical. He can sit at a...

Are Decoders Better?

Are Decoders Better?

Are decoder irrigation controllers better than conventionally wired irrigation controllers? Yes - For the right project they are definitely better   Irrigation controllers have improved exponentially over the last few years. Smart irrigation controllers that give...