When you hear the term backflow, what does it make you think of? Many homeowners aren’t familiar with the expression, but it refers to something that could be a serious problem for you. Backflow happens when there is a large drop in water pressure, such as when there is a leak from a water main, or the fire department hooks up to a fire hydrant and uses a lot of water. Backflow could cause sewage to be pulled back into your freshwater supply, if not for a simple device called an atmospheric vacuum breaker. These devices are built so as to allow air back into the system, thus breaking the vacuum that would have been sucking the water back into your home. It is a simple but genius design. If you see one of these pipes near your home, you shouldn’t interfere with it, since it plays a vital role in keeping your water supply safe.