Choosing the Right Backflow Preventer Valve


Backflow preventer assemblies are most frequently required in conjunction with a lawn irrigation system. Many homeowners use extensive sprinkler systems to water their lawns and gardens. In many cases, there’s no inbuilt separation between the irrigation system and the potable water supply– creating the potential for backflow, a situation in which water moves backwards back into your sprinklers.

When this occurs, that water can carry fertilizers, pesticides, herbicides, and other contaminants into clean water, a serious health hazard. To prevent this backflow from occurring, you may be required to install a backflow prevention valve backflow). There are several different types of backflow valves, each of which is useful for different situations.

When Can Backflow Occur?

Backflow isn’t a normal phenomenon; usually, water moves in the “correct” direction, from municipal water supplies into your sprinkler system. However, several situations create the possibility for a reversal of normal water flow:

  • Use of a nearby fire hydrant. If the local fire department needs to use a nearby fire hydrant, it can create drastic changes in water pressure. When the water is turned back on after hydrant use, the pressure loss that results can create back siphonage.
  • Water main break. A burst water main is another situation that alters water pressure gradients, such that backflow might occur in systems like your lawn irrigation.
  • Sprinklers are installed on a sloped area. Like everything else, water flow is directed by gravity. If your property is sloped, you may need a backflow prevention device to prevent contaminated water from flowing back down into clean water supplies.