You should have a backflow preventer on your irrigation system if your water comes from a “potable” (drinkable) source (see next paragraph.) If your irrigation water source is considered potable, then in most places it is illegal to not have the proper local authority-approved type of backflow preventer on your irrigation system. If your water source is non-potable, you generally are not required by law to use a backflow preventer (but not always, some jurisdiction even require them for non-potable water like recycled, reclaimed, and gray water sources).
There are many types of backflow preventers. Almost everywhere the local authorities will dictate that certain types of backflow preventers may NOT be used with irrigation systems within their jurisdiction. In some cases, the authorities will dictate the exact type of backflow preventer you MUST use. You may hear or see the term “Cross-Connection Control“, this essentially is referring to backflow prevention. A cross connection is a connection between a drinking water supply and a source of pollution or contamination.
What’s potable water? Definition: potable water means the water is suitable for drinking. Depending on local law, that may include drinking water for animals. If you would be willing to drink it without treatment, then it is probably going to be considered potable. Non-potable water is water that is not suitable for drinking. (Once water enters into your irrigation system it is considered to be non-potable, more on that later.) Examples of water sources that are often considered non-potable are lake and pond water, water from streams, and well water from a contaminated aquifer that is not suitable for drinking. Most other wells do require a backflow preventer, even if the well doesn’t provide drinking water. This is to protect the aquifer the well takes the water from, because even if you don’t get drinking water from the well, your neighbors may get drinking water from the same underground aquifer. If you plan to apply fertilizers or pesticides using your irrigation system, then in most cases you must have a backflow preventer- regardless of the water source. Nobody wants those chemicals going into lakes, streams or the water table!
Why do you need a backflow preventer?
Your landscape has all kinds of nasty things in it that will make you sick or worse if you drink them. Thus irrigation water is officially considered a contaminant (creates a health hazard) rather than just a pollutant (is objectionable in color or odor). What’s in irrigation water? How about toxic chemicals (fertilizers, pesticides, etc.) and animal waste? (Not that I want to gross you out, but every day millions of dogs lift their legs in a fond salute to their favorite sprinkler head!) These things can and WILL come back up your irrigation pipes and into your drinking water if you don’t stop them. If you have a well, they can go down your well and into everyone else’s drinking water. If you are on a community water system they could go back up into the pipes and poison your neighbors. The valves that turn on and off your irrigation system are not sufficient to stop backflow. The purpose of the backflow preventer is to protect you when the valve breaks or leaks, which all valves will do eventually. Saving a little money by skipping the backflow preventer will not seem so smart after you spend a small fortune on hospital bills (or funeral expenses) for a poisoned family member or pet!
Now wait a minute, some people say, doesn’t the water pressure in the water system keep the irrigation water from going backwards? Yes, most of the time it does. But there are times when the water pressure drops in the supply system, and this is when the backflow occurs. No, it is not a frequent occurrence. For example when the water company has to shut off the water to repair a water pipe or hook up a new pipe. This makes construction projects easily the most common cause of backflow problems. Fire fighting is another common cause of backflow. Fire trucks use huge pumps to suck the water out of the fire hydrants. This often causes the water pressure in the surrounding areas to drop, and backflow will occur in the surrounding neighborhoods.
You can do a quick experiment yourself and create backflow in your home pipes. Simply turn off the water valve leading to your house. Next have someone turn on a faucet. Now turn on a different faucet that is higher than the first. You will hear air being sucked into the higher faucet. You just created backflow in your house piping. Pretty easy, wasn’t it?
Another common argument against the need for backflow preventers is that if all the valves are closed the water can’t go backwards through them, so the valves should prevent backflow. The obvious problem with this is that if the backflow occurs at a time when the valve is open, like when the sprinklers are on, the valve will not stop backflow! But even when the valve is closed it may not prevent backflow. A standard manually operated valve should stop backflow when it is closed– if the valve is fully closed, has good seals, and does not leak. However most of the automatic valves, such as the electric solenoid valves used for irrigation systems, will not stop backflow even when “off” and fully closed. This is because these solenoid valves are directional in design. If you look on the valve you will see that it has an arrow on it showing the flow direction. If the flow is reversed, the valve will often open slightly (that’s why the valve has the arrow on it- to warn you not to install it backwards!). Thus when backflow occurs and the flow direction reverses, an automatic valve will not stop the backward flow.
All sprinkler systems that are hooked to city water require a backflow preventer. This device prevents harmful things such as fertilizers to get into our drinking water. All local city utilities require the installation of backflow preventers for sprinkler systems and to be sure they are working correctly.
This device prevents harmful things such as fertilizers to get into our drinking water.
What is backflow?
Backflow is when water flows backward into the public water supply. This is usually caused when pressure in a home plumbing system is higher than the pressure distribution system. The difference in pressure can be due to a pressure drop in the distribution system. Pressure reduces when a water main bursts, pipes freeze or there is unexpectedly high demand on the water system. For example, if water is drawn from a hydrant near your home, the pressure in the distribution system could be less than in your plumbing system. The higher pressure from your personal plumbing may allow contaminated water from the ground, from storage or from other sources to be drawn into the main system.
Can I really contaminate the public water supply?
Yes. Every time you wash your car or power wash your deck, you become vulnerable to back siphonage. For example, if you leave a hose in a soapy bucket of water, or connected to pesticide sprayer, the polluted water can be pulled back through the system and contaminate the public water supply. Keep in mind that back siphonage can happen at home, business or restaurant. Outbreaks of gastrointestinal distress, hepatitis A and Legionnaires disease have been reported due to instances of unprotected backflow.
Typical backflow preventer applications
•Irrigation sprinkler systems •Air conditioning systems •Laboratory equipment •Photo developing equipment •Boilers -Swimming pools •Solar heat systems •Fire sprinkler system •Soda vending machines
Who can test my backflow preventer?
Testing of your backflow must be performed by a technician licensed and certified in the testing and repair of backflow assemblies. Most city utilities and water purveyors recommend annual inspection and testing of your backflow devices. (Depending on the size of your community you may be required to test your devices.) Certified documentation of the testing of your backflow preventer will be kept on file at our office. Northwest Iowa Sprinkler is one of only a few irrigation and backflow testing companies in Northwest Iowa. Call today to make an appointment to have your backflow preventer installed or tested.