What Is Backflow

The unwanted reverse flow of water within a plumbing system due to sudden pressure fluctuations. This may cause backflow conditions and likely a health risk allowing contaminants such as chemicals, bacteria and/or wastewater to enter the water supply.

Backflow Test Purpose

• Testing ensures internal components such as check and relief valves are operating properly to eliminate the contaminantion risk. 
• Internal components include rubber gaskets and o-rings that degrade/deteriorate over time, seats that experience wear, erosion and pitting that effect the positive seal of the check. In addition check valve guides experience mechanical wear and mineral scaling due to constant friction and water exposure.
• Rebuild kit installs will be periodically necessary in order to effectively maintain your backflow preventer. 

Examples:

• A garden hose left in a pool, bucket of soapy water, or laundry basin creates a cross-connection. If the pressure in the water main drops, the hose can act like a straw, siphoning the contents of the pool or bucket directly into the household/neighbor's potable water lines.
• If an irrigation system lacks a proper backflow preventer then a drop in water pressure (caused by a main break or high demand) can draw stagnant, dirt-filled water from the sprinkler head back into your home’s drinking water system.

A commercial backflow incident occurs when a cross-connection, a contaminant, and a pressure change combine to pull hazardous material into a public water supply.

Examples:

• Pesticides or fertilizers from irrigation systems can be sucked back into the water supply during pressure drops.
• Backpressure: Occurs when an external system (like a boiler, pump or pressurized tank) has higher pressure than the municipal supply, forcing non-potable water into the clean system.