If you have a toilet with a tank on the back in your home or business, it contains a valve to fill the tank every time you flush. The fill valve, or “ballcock,” is equipped with an approved backflow prevention device that prevents any water in the tank from being siphoned back into the pipes of your house (anti-siphon). Plumbing codes require all water outlets to be equipped with a backflow prevention device to prevent contamination or pollution of the drinking water.
Therefore, all sinks have a space between the end of the faucet and the flood level of the sink called an air gap. Some sinks typically found in commercial businesses, such as a mop sink, are equipped with a backflow prevention device called an atmospheric vacuum breaker installed on the faucet.
All hose bibs (sillcocks) are required by code to have a special backflow prevention device installed called a hose connection vacuum breaker. This device prevents water in the hose from flowing backward into the pipes of your house.
All commercial fire-sprinkler systems are required to have backflow prevention devices installed.
In other types of commercial and industrial businesses, it is necessary to ensure the safety of Fairfax Water’s potable water system by requiring the installation of backflow prevention assemblies in the main water-service line to certain types of buildings. The types of backflow prevention devices installed at these locations can range in size from ¾ inch to 10 inches in diameter and cost anywhere from a couple hundred dollars to tens of thousands of dollars to purchase and install.
These are just a few of the examples of where one might find backflow prevention devices in either a home or business.