What Is Backflow Testing?

Backflow testing is the process of verifying that a backflow prevention assembly is functioning correctly and protecting the public drinking water supply from contamination caused by reverse water flow.

What is backflow?

Backflow occurs when water flows in the opposite direction from its intended path. In a normal water system, water flows from the utility supply into your property. Under certain conditions, such as a sudden drop in water main pressure, the direction of flow can reverse. This reverse flow can draw water from irrigation systems, fire suppression lines, or other sources back into the potable water supply.

If that water contains fertilizers, pesticides, antifreeze, rust, or other contaminants, it can pose a serious health risk to anyone drinking from the affected supply.

What is a backflow preventer?

A backflow prevention assembly is a mechanical device installed on a water line to stop reverse flow from occurring. These devices use check valves, pressure relief mechanisms, and other components to ensure water only flows in the intended direction.

Common types include:

• Pressure Vacuum Breaker (PVB) — common on irrigation systems
• Reduced Pressure Zone (RPZ) assembly — used on higher-hazard connections
• Double Check Valve (DCV) assembly — used on lower-hazard applications

What does backflow testing involve?

During a backflow test, a licensed technician connects test equipment to the assembly and measures the pressure differential across each check valve and relief valve component. The results confirm whether each part of the device is functioning within acceptable parameters.

The process is typically completed in a single visit and does not require excavation or major disruption to your water service. After testing, you receive a written report of the results that can be submitted to your local water authority.