Backflow FAQs


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Q: What is a cross-connection?

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A: It is a situation where there is a direct arrangement of a piping line, which allows the potable water supply to be connected to a line, which may introduce a contaminant.

Q: What is the most common form of a cross-connection?

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A: Ironically, the simple garden hose is the most common offender, as it can be easily connected to the potable water supply and used for a variety of potentially dangerous applications such as filling swimming pools or fertilizing the annuals.

Q: Who is responsible for determining whether or not a device is needed?

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A: The South Farmingdale Water District is required to determine the degree of hazard that a facility may pose to its public water supply system and will decide on the installation and maintenance of an acceptable backflow prevention containment device. Ultimately, the customer has the primary responsibility of preventing contaminants from entering the potable water supply.

Q: Why does the South Farmingdale Water District have a cross connection program?

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A: As mandated by state law, “the supplier of water shall protect the public water system by containing potential contamination within the premises by requiring backflow prevention devices installed and tested.”

Q: How often does the device need to be tested?

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A: The law requires that a certified backflow tester inspects and tests all installed RPZ or DCV backflow services annually.

Click here to download list of Nassau County Certified Backflow Testers

Q: Why do I need a backflow prevention device?

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A: New York State requires the devices to protect the public water supply against contamination.

Q: Are there different types of backflow prevention devices?

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A: The most common type is a Double Check Valve (DCV), which is used on residential properties.  The second most common is a Reduced Pressure Zone (RPZ) and is generally found in commercial properties.  Finally, the newest type of backflow device is a Pressure Breaker Valve (PBV) that can be installed on lawn irrigation systems if no other hazards exists.