What is a backflow preventer?
A valve installed on irrigation systems to prevent water contaminated with fertilizers, pesticides, or other chemicals from flowing backward into the public or private drinking water supply.
A backflow preventer is a one-way valve installed where a sprinkler system connects to the main water supply. It stops contaminated irrigation water from reversing flow and entering the drinking water lines, a hazard known as backflow.
When pressure drops in the main water line (during repairs, high-demand periods, or system shutdowns), water can flow backward out of underground pipes and into the home's or facility's potable supply. If that irrigation water contains fertilizers, pesticides, herbicides, or other lawn chemicals, it introduces those substances directly into drinking water. Even small amounts pose health risks.
Connecticut requires backflow preventers on all sprinkler and irrigation systems by state plumbing code. The device must be installed at the point where irrigation water enters from the supply line, typically near the water meter or at a dedicated irrigation supply valve. Two common types are atmospheric vacuum breakers (simpler, cheaper, suitable for single-family use) and reduced-pressure principle backflow preventers (more expensive but mandatory for commercial systems and high-risk settings).
Many municipalities in Connecticut also mandate annual testing and certification of backflow preventers, particularly for commercial properties and community systems. Licensed irrigation sprinkler contractors are familiar with local testing requirements and can handle installation and maintenance to ensure compliance.