Backflow preventer is a mechanical device with moving parts that prevent contamination of the water by installing the valve in a cross connection. This prevents the contamination of public water. Water companies put numerous amounts of monies and resources to protect public water. Installing and having well operating backflow valves is important to protect the public water.
Backflow preventer is likely to break at some point, just like any mechanical device and according to the laws you need to check it at least once a year by a certified backflow tester that is licensed within the state, NJ, NY, or any other state.
Backflow test results report needs to be submitted by a certified backflow tester to the town or the DEP and once a year you will also need to have your report submitted to the town in case you install a new backflow device.