Irrigation System Backflow Testing
The four most common types of backflow devices are atmospheric vacuum breakers (AVB), pressure vacuum breakers (PVB), double check valve assemblies (DC), and reduced pressure principle assemblies. Don’t waste your time learning about AVB’s or PVB’s. All we need to know about those types of assemblies is what they look like. Once identified, we know that these devices do not comply with the water safety regulations set forth by Missouri water purveyors. When it is convenient to locate your backflow device at the highest point in your irrigation system, AVB’s or PVB’s may still have minimal use on private water systems.
The government regulations on backflow protection state that any water source providing for ten or more individuals is considered a public water source. Thus, backflow compliance would be necessary to have a legal connection to that water source. Backflow regulations will vary depending on your location, but everyone must at least meet the minimum standards set forth in Federal and State legislation.
This leaves us with two devices left to choose from when installing an irrigation system: DC’s and RP’s. DC’s are the most popular in the Springfield area. The main benefit to the DC is that is has a closed system. The closed system allows for the device to be buried or flooded temporarily without causing any problems. We don’t recommend burying your backflow in the ground without burying it inside a properly installed valve box. However, a lack of building code in the area has led to many improperly installed valve boxes. In other words, the boxes are filling up with dirt, thus burying the backflow preventers. This is often the situation when we take over the maintenance of an irrigation system. With a DC backflow, the dirt in the box only becomes a problem when the prevention assembly device needs to be repaired.
RP devices are quite the opposite of the DC device. They should be mounted about 18 inches above ground level, (or whatever local codes require). These devices actually provide the greatest form of backflow protection out of all the devices mentioned. When there are pressure fluctuations in the water lines, RP devices spit the backwards flowing water out the bottom of the assembly. The big problem with RP devices is that they tend to be exposed to the cold of winter. Without a warming box to cover the RP device, the brass splits open from freezing water. Winterization is meant to protect this from happening, but it’s just not always enough.
All of these backflow devices function with one similar feature: a check valve. If you do not know what a check valve is: a check valve is a plumbing part which is usually held closed by a spring on one side. The spring pulls the valve back towards the source of the water. Usually the strength of the spring is less than that of the water source, allowing the water to push the valve open and flow on through.
In the event that water is pushed backwards through the system, by an air compressor, while winterizing, for example, the backwards pressure pushes the check valve closed. In the event that there is a water main break, there is usually a siphoning-effect which pulls water backwards through the water lines. This siphoning-effect would also cause the valve to close. When the valves close, no dirty, stagnant, polluted, or black water can flow backwards into the rest of the water system. This is why they are called backflow prevention devices. We must test the check valves inside of the backflow assembly device on a regular basis to ensure they are able to perform their intended duty.
Why do we need to test backflow preventers?
Irrigation system backflow testing is a requirement of the public water supplier to protect our drinking water. Any lawn irrigation system connected to the public water system is required by law to be protected by a backflow prevention device. These devices must be tested annually. The test results must be reported to the local water purveyor. For residential customers in Springfield, this must be turned in by June 1st each year. If you do not test your backflow devices annually, do not be surprised if the water purveyor comes to shut off your water. Do not think of it as another punishment or tax from the city though. Think of backflow testing as your good deed to society for the day. Every time you have your backflow device tested, you are protecting the community’s drinking water. Backflow testing ensures that our children and the children of our children, etc, have an ample supply of clean drinking water in the
Normal lawn sprinkler systems are considered a low risk hazard to our drinking water because they typically are only capable of contaminating the water supply with a little bit of dirt. Occasionally, irrigation systems will have extra lines that hold water because the old heads are capped or closed. These lines can hold stagnant water for an extended period of time until it is eventually considered “black water.” Black water is comparable to a poison. It is definitely not something we want in our drinking water. Black water contamination is the greatest concern when protecting lawn sprinkler systems with backflow devices.
Higher hazard backflow risks do exist in irrigation systems which utilize the distribution of fertilizers and pesticides via sprinklers. These types of systems are more common on golf courses and other sports field. The pesticides and fertilizers in the sprinkler lines are what make these irrigation systems considered high hazard risks. Backflow devices are also used for protecting many other systems including fountain drink machines, toilets, and fire suppression systems. We do not test any of those systems at Gabris Landscaping. We focus solely on the backflow maintenance for lawn and landscape irrigation systems.
Our certified backflow inspectors can test and report these results for you as a part of our basic irrigation maintenance services. In the event that your backflow device fails inspection, we can repair or replace it as well. It is quite common for a seal or spring on a backflow prevention assembly device to bust or break. We try to keep repair kits in stock for the most common devices. Depending on model and age, a backflow prevention device is occasionally less expensive to replace than repair. Keeping your backflow valve box free of debris can speed up repairs and keep repair costs to a minimum. Maintaining a decent size limestone gravel layer inside the box underneath the backflow can absorb moisture which prevents the individual parts in a backflow assembly from rusting together. When you can not take apart the backflow because it is rusted-stuck together, the device is considered un-repairable.
Lawn sprinkler backflow testing is included as a part of our basic irrigation maintenance program. We also provide irrigation backflow testing services for clients who do not wish to be included in our annual sprinkler maintenance program.