Backflow Prevention FAQs

What is the reason for a backflow Device?

Americans receive clean fresh water from utilities or local wells. The water supplier has very little control over what we do with the water once it enters your premise. We assume that water only travels in one direction but the reality is a small decrease in water pressure can cause the potable water in your pipes to flow in the reverse direction. Property owners regularly inadvertently contaminate the water supply by inserting a hose into a pool to drain it, into a sewer to clean it, or into a pail of pesticide. Once water has been compromised, it can easily travel back up the hose, and make its way into the municipal water supply. Backflow devices make sure the water only flows in the direction intended, protecting our neighbors from the strange things we do with water.

Next time you stomach feels queasy it may be the result of a backflow condition and not that red-hot Taco.

Person got sick for backflow problem in the water

What is backflow prevention?

The water in our domestic water mains is classified as “potable”, or safe to drink. Once it enters our buildings, it becomes cross-connected via copper piping to plumbing fixtures such as hot water heaters, boilers, washing machines, lawn sprinklers, garden hoses and swimming pools. That’s where the clean water becomes contaminated with rust inhibitors, bleach and chemical surfactants, animal waste, and other contaminants. Under normal conditions, the contaminated water stays where it is and is eventually and safely discharged into our sewers. When water pressure within a NYC building exceeds the water pressure delivered by the water main, the water within the building will reverse direction and pollute our clean, drinking water. The resulting back-siphonage is called ‘backflow’. Backflow prevention devices are designed to prevent back-siphonage as well prevent reverse flow due to back-pressure.

What causes a reduction in supply pressure?

Water main breaks, thermal expansion from hot water boilers/ heaters or an open fire hydrant are main causes for pressure reduction and potential backflow hazards. Drinking water contaminated with “backflow particulates” can be hazardous, making backflow prevention a legal mandate throughout the entire country.

Am I required to have a backflow device installed?

Every building inside the five boroughs of NYC is required to install primary backflow preventers on each water main that feeds the property. If you have a fire/sprinkler system in place, you’ll need to install a primary backflow preventer immediately downstream from the DEP meter or fire/sprinkler supply branch.

*Please be aware that a DEP “Order to install a Backflow Preventer” provides a finite period of time to complete the work before a violation is issued. If you ignore it, the DEP can and will shut the water to your entire building.

What is a primary backflow preventer?

A primary backflow preventer is a plumbing device consisting of two to three internal valves that absolutely prevents the water inside your building from reversing flow and contaminating the local water supply. It’s installed immediately downstream from the DEP water meter. These devices are aggressively managed by NYC DEP’s Cross Connection Control Unit (CCCU) in Flushing, Queens.

What is a secondary backflow preventer?

Secondary backflow devices protect the drinking water in your building from getting contaminated by dangerous, hazardous or objectionable substances that are already inside your building. Secondary devices that protect the buildings’ internal drinking water from contamination are managed by NYC DOB and should be tested annually.

How do I know if I need an RPZ (Reduced Pressure Zone) or DCV (Double Check Valve).

The threat level posed by dangerous, toxic or objectionable substances that exist inside your building will determine which type of backflow device you need. Most buildings require an RPZ on their domestic supply lines and a DCDA (double check detector assembly) or RPDA (reduced pressure zone detector assembly) on the fire/sprinkler supply lines. The DCV is the recommended solution for low hazard conditions and the RPZ is the recommended solution for high hazard conditions, since it has a relief valve that will dump contaminated water down the drain vs. siphoning it out of your building. Your inspector will determine which type of device is required for your property.

How many backflow devices are required per property?

A backflow preventer must be installed on each water supply line, including your domestic, fire/garden sprinkler system.

What is the best way to prevent backflow?

Air gaps, Vacuum Breakers, Double check valve Assemblies (DCVA), and Reduce Pressure Zones (RPZ) are some of the most common types of devices preventing backflow. The following chart lays out the pros and cons of each device.

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Backflow Testing FAQs

How often does a backflow device need to be tested?

NYC DEP mandates that ALL backflow devices be tested every 12 months by a NYS Certified Backflow Tester who is employed by a NYC Licensed Master Plumber. The test results must be overnighted in the form of annual testing reports (GEN215B’s) to NYC DEP’s Cross Connection Control Unit in Flushing, Queens.

How do I get my backflow device tested?

Contact Ashokan Water Meter and Backflow to schedule an annual inspection of your backflow device. We will also submit the required documentation to the DEP so you will have proof of compliance.

How are annual tests* performed?

Each backflow preventer has four test ports, which are used to connect a pressure kit that has the ability to create backflow pressure in each test port to simulate a real backflow situation. The Certified NYS tester watches the gauges closely to make sure each internal valve opens and closes correctly.

*Please note that the water supply to the entire building must be shut, as there cannot be any downstream demand while we test. When we call to schedule the tests with you, we encourage you to post a brief water shut-off notice in your building so your tenants are aware of the very brief shut down.

*Please be aware that a DEP “Order to install a Backflow Preventer” provides a finite period of time to complete the work before a violation is issued. If you ignore it, the DEP can and will shut the water to your entire building.

My backflow preventer is dripping, what does that indicate?

It’s likely that there’s dirt and debris build-up accumulating internally, which can freeze the moving parts of your device in place, and prevent check valves from opening and closing. When check valves no longer open and close freely, your device may leak slightly. An RPZ can actually dump a very high rate of water from its Relief Valve and when that happens, it’s likely that you may need to clean or replace some of the internal components.

Can I remove a backflow violation?

It is possible to have a violation dismissed and it’s also possible to actually receive a reduced fine, as long as you test and file those tests prior to the initial hearing date. A dismissal can occur when the DEP makes a mistake by issuing a violation, despite the fact that the device had been tested.

Am I required to test downline devices?

Yes, you are required to test secondary backflow preventers. DOB(Department of Buildings) is the controlling authority for downline devices and they send inspectors out for physical inspections of buildings. When the inspector arrives, he/she may ask for your completed annual test reports and if you do not have them, they will issue an IWN.

How long does a backflow device test take?

The average time for a backflow device test is approximately 5 to 10 minutes per device. This duration may vary slightly depending on the specific type of backflow device and the complexity of the testing procedure. However, in general, the testing process is relatively straightforward and can be completed quickly.

Here’s a breakdown of the typical steps involved in backflow device testing:

    1. Preparation: The technician will gather the necessary equipment, locate the backflow device, and secure access to the testing ports.

    1. Connection: The technician will connect testing gauges and hoses to the appropriate ports on the backflow device.

    1. Pressure Verification: The technician will check the upstream and downstream water pressure readings to ensure they are within the acceptable range.

    1. Functional Testing: The technician will perform specific tests to evaluate the proper functioning of the backflow device’s valves and check for any leaks or malfunctions.

  1. Documentation: The technician will record the test results and complete any required paperwork, including a GEN-215B report if applicable.

Does the water service get interrupted while preforming a backflow test?

Yes, the water service to the line connected to the backflow device being tested will be temporarily interrupted during the testing procedure. This interruption is necessary to ensure the accuracy and safety of the testing process.

Reasons for Temporary Water Shut-off:

  1. Pressure Isolation: Temporarily shutting off the water allows the technician to isolate the backflow device from the rest of the plumbing system, ensuring that the testing is conducted on the device alone.
  2. Testing Accuracy: By isolating the backflow device, the technician can obtain precise pressure readings and evaluate the device’s performance without interference from other water sources.
  3. Safety Precautions: Disconnecting the water supply eliminates the risk of accidental water pressure surges or leaks during the testing process.

Duration of Water Interruption:

The water service interruption is typically brief, lasting around 5 to 10 minutes per backflow device. However, the exact duration may vary depending on the complexity of the testing procedure and the specific location of the backflow device.

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Is a backflow preventer required in NYC?

The Department of Environmental Protection (DEP) mandates the installation of backflow devices at the point of entry of your water service. These devices are referred to as Primary Backflow Devices and protect the public water supply from your contaminating it. Backflow devices are also mandated within your property to protect you from contaminating your own water supply.  These devices are mandated by the Department of Buildings (DOB)  in the Plumbing Code and called Secondary Backflow Devices. An example of a secondary device is a backflow device on an irrigation system to protect you from the pesticide, and a backflow device on a boiler feed to protect you from the boiler chemical treatment.


In New York City both primary and secondary devices must be tested on an annual basis. Reports for Primary Device Test must be submitted to the DEP. Secondary device tests reports must be kept on file by the property owner. Failure to test and file reports may result in fines or legal exposure in case of a backflow incident. 


The type of primary and secondary device is dependent on the type of hazard. Hospitals, chemical plants and dry cleaners present a large hazard and hence have very stringent hazards. Homeowners with one water line and no pool or irrigation present a minimal hazard and are mandated to meet lower hazards. The following chart issued by the DEP outlines your Primary backflow responsibility.


Avoid a Fine of DEP Backflow Violation 

Worried About a New Violation?

We have your back and we’ll help you manage your backflow violation by remedying the issue that drove the violation so you can prevail at the hearing.


Received a DEP Order?

DEP’s Cross Connection Control Unit (C.C.C.U.) will extend a 30 day period to submit professional drawings and application forms for backflow preventer installation. We handle all submissions and approval notices from start to finish.


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