Febco 0122965
Febco 0683040
Febco 0683039
A backflow preventer is a valve assembly on the main irrigation line that stops used or contaminated water from flowing backward into the clean water supply. When city pressure drops, it keeps lawn water, fertilizer, and pesticide out of your drinking water.
Most local codes require one so irrigation water cannot siphon back into your drinking supply. The required type and size depend on your code and the hazard level. Confirm with your local water authority before you buy.
A pressure vacuum breaker is the most common choice for typical residential irrigation and must sit at least 12 inches above the highest head. A reduced-pressure (RP) assembly offers the highest protection for high-hazard connections and anywhere back-pressure is possible. Your local code sets the requirement.
In freezing climates, shut off and drain the assembly before winter, or wrap it in an insulated freeze bag. The exposed brass body and test cocks are the first parts to crack.
Many jurisdictions require testable assemblies to be tested by a certified tester at installation and then annually. Check your local water authority’s rule.
Match the assembly to your service or mainline size. That is commonly 3/4 in or 1 in for residential irrigation. Sizing larger than the line adds cost without adding flow.
It installs on the main line, upstream of the zone valves. A pressure vacuum breaker sits at least 12 inches above the highest head; a reduced-pressure assembly mounts above grade with clearance for its relief drain. Many areas require a licensed installer and a certified test after install.
The right assembly depends on your hazard level and local code. The four common types:
Confirm the required type, size, and testing rules with your local water authority before you buy. Servicing an existing unit? We stock relief valves and replacement parts.
In freezing climates, drain the assembly or wrap it in an insulated freeze bag before winter. The exposed brass body and test cocks crack first. A backflow preventer mounts upstream of the valve manifold. To size the box that protects it, see our How to Choose a Sprinkler Valve Box guide.
