Backflow preventers are a crucial part of any irrigation system. To understand what a backflow preventer is, there are some key terms that need to be understood.
is any connection between a potable (drinkable) water system and any system containing nonpotable water, pollutants, or toxins. An example of where a cross-connection would exist is the piping between consumers’ water systems and an auxiliary water system, a cooling system, or an irrigation system.
is defined as any unwanted reversal of the flow of liquids, solids, or gases in a piping system. Backflow in an irrigation application is when water from the sprinkler system travels “upstream” through the pipes and enters the potable water system through a cross-connection.
is when the pressure downstream of the backflow devices exceeds the supply (or upstream) pressure. This can occur if the supply pressure is reduced, or if the pressure downstream is increased.
occurs when a vacuum is created upstream of the backflow device, and water is literally sucked back up the system. Back siphonage can happen when the water supply is stopped due to a water main break or nearby fire hydrant use.
are mechanisms designed to prevent contaminants from entering the potable water system in the event of back pressure or back siphonage.
Most homes have only one system for both potable and irrigation water, instead of two separate systems to avoid the risks associated with a cross-connection. Because there is no separation, there is a risk that everything running through your sprinkler system (fertilizers, pesticides, and herbicides, as well as anything that has seeped into the ground, such as animal waste) will backflow into your potable water system. The only way to prevent this from happening is the use of some type of backflow prevention device. The shutoff valves included in sprinkler systems are not enough to prevent backflow.
Most areas require the use of backflow preventers on all water systems, but even if your area doesn’t have these building codes, they’re a mandatory precaution for a health-conscious person.
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