What Is Backflow

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The unwanted reverse flow of water within a plumbing system. Sudden pressure fluctuations may cause backflow conditions and likely a health risk allowing contaminants such as chemicals, bacteria, viruses and parasites 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 or rubber kit installations will be periodically necessary in order to effectively maintain your backflow preventer. 

Examples:

• Backflow occurs when a cross-connection is created by a garden hose submerged in a pool, a bucket containing chemicals, or left below the flood rim of a sink. If pressure in the water main drops like when fire hydrants are opened, the hose can act like a straw, siphoning contaminated water from the pool, bucket, or sink directly into the home's potable water system—and potentially into neighboring water lines.
• An irrigation system can become a serious cross-connection hazard if water pressure drops due to a water main break, firefighting activities, or high system demand. Contaminated water can be siphoned back through sprinkler heads and into the potable water supply. This water may contain animal waste, fertilizers, pesticides, dirt, bacteria, and other contaminants that can enter your home's drinking water.

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:

• Backsiphonage: Some fire systems contain antifreeze, foam or other non potable solutions made for fire fighting. Most fire systems contain stagnant, tainted water and with negative pressure, (water main break) fire suppression water can enter the potable supply without proper backflow prevention.
• Backpressure: Backpressure backflow occurs when an external system, such as a boiler, pump, or pressurized tank, creates more pressure than the municipal water supply. This can force harmful substances, including chemical treatment inhibitors or industrial conditioning agents, back into the clean water system.