Control water flow with greater precision in your irrigation system
Though they are not always visible, sprinkler valves are an integral part of your irrigation system. They control and regulate the amount of water that each zone receives and may be controlled manually or electrically with a timer. In addition to regulating water flow, valves are also used to turn off your system in emergencies as well as prepare it for winterization. Different types and sizes are appropriate for different uses, so it’s important to know what to use and where to use it. You’ll also need to consider the best way to prevent backflow. Use the following questions to help determine what issues to keep in mind as you shop for valves:
Valve Types, Considerations and Backflow Prevention
Anti-siphon and in-line valves are both viable options. In addition to valves that control the flow of water, you’ll also need to install emergency shut-off valves and you’ll want to consider a drain valve. Size, flow control and whether a valve “bleeds” internally or externally are other important considerations. Beyond valve issues, you’ll need to choose a method to prevent backflow, which can taint your drinking water. While anti-siphon valves have built-in backflow prevention (also called cross-connection control), you may need or want to install additional protection. Local laws and regulations may dictate which types of valves and backflow preventers you can or cannot (or must) use, so be sure to consult them prior to installing your sprinkler system.
Anti-Siphon Valves: With built-in backflow prevention, these valves help ensure that your drinking water stays safe. They are fairly easy to install and may be either manual or electric. Anti-siphon valves are installed above ground, making them easy to maintain. They are most often made of PVC, but they may be constructed from brass or bronze as well. Use anti-siphon valves in areas where sprinkler lines are located under gardens and lawns where pesticides, weed killers and other chemicals are consistently used. They are available in both 3/4" and 1" sizes.
In-Line Valves: Unlike anti-siphon valves, in-line valves are usually installed below the ground and do not feature built-in backflow protection. This type of valve is generally used in conjunction with a backflow preventer, such as an atmospheric vacuum breaker. Valve boxes protect them to provide greater durability. Their in-ground installation allows them to be located anywhere within the landscape without detracting from its appearance. A manifold is a group of in-line control valves that stem from the main supply line to provide easy access and maintenance.
Other Valves: In addition to valves that regulate the flow of water, there are a few other types of valves necessary for proper operation of an irrigation system. Emergency shut-off valves cut the water supply to all or part of the system temporarily to prevent damage or to allow for maintenance and repair. They may be either gate or ball valves. Drain valves are located at low points on the main and lateral lines and are used to drain water from the system to make repairs or for winterization in colder climates. Indexing valves connect to multiple individual zones to allow water to progress through each zone.
Valve Considerations: Deciding how large a valve should be depends on your system’s flow rate. 3/4" valves are ideal for most residential applications where the flow rate is around 8-10 gpm (gallons per minute). If, however, the flow rate exceeds 15 gpm, you’ll probably want to use a 1" valve. Installing flow control will allow you to customize performance by ensuring that the right amount of water is used in each zone. If valves are activated manually, they may be done so using the manual bleed feature.
Backflow Preventers: When sprinkler heads operate, they sometimes create a vacuum that can cause water that has already been expelled to be sucked back in. This water, which may have picked up chemicals from pesticides, fertilizers and other lawn products, can filter back into your drinking water and cause illness. Backflow may be caused by pressure generated by equipment (pressure backflow) or pressure exerted upon water (back siphonage). Backflow preventers stop this from happening and, in many cases, are required by local codes and regulations. Use the chart below to explore a few different types.
|Type of Backflow Preventer||Function||Points to Consider|
|Atmospheric Vacuum Breaker (AVB)||Opens a vent that allows air into the system to prevent siphoning; installs between the circuit valve and delivery device||
|Double Check Backflow Preventer||Uses two spring-loaded, independently operating check valves to block backflow if water pressure temporarily drops||
|Pressure Vacuum Breaker (PVB)||Installs on the pressure side of emergency shutoff valve to prevent back siphonage||
|Reduced Pressure Backflow Preventer (RP)||Features two check valves and a pressure differential relief valve that operates automatically; installs between two emergency shutoff valves||
Built-In Pressure Regulators: Valves with pressure regulators control the pressure level directly, rather than relying on a system regulator that may be too far away to effectively regulate pressure at far ends of the line.
Molded Bolt: Valves with the stud part of a bolt molded to their bodies will not fall off when removing the nut, meaning you won’t accidentally lose it in the wet, muddy ground nearby.
Internal Scrubbers: If you draw water from a pond or irrigation ditch, look for valves with scrubbers that automatically remove algae to prevent buildup from blocking the opening.
A timer will allow you to set your irrigation system to run when you want it to, even when you’re not home.