A backflow preventer of (BFP) is an important device for the water system of your building. It prevents the domestic water entering your building from flowing back into the municipal system and contaminating the municipal system. It causes the fresh water to flow in one direction into the building. The main job of this device is to prevent drinking water from being contaminated due to a backflow.
When water enters your building from the main municipal water supply line, it should only flow in one direction. At times, due to pressure changes, the water can actually flow backwards and seep back into the main water supply line.
Examples of a backflow are:
- when there is a water main break.
- When a fire hydrant is opened for use.
Because pressure is lost of very low during these events, water is no longer pressured so that it is being pushed into your building. When this happens, water will flow backwards into the municipal water system.
Just think of the device as a one way fresh water gate keeper. Many older buildings may not have a backflow preventer. The plumbing code requires this BFP deviice on all new buildings, and for older buildings undergoing a large plumbing project such as domestic water line of drain line replacement.