Backflow occurs when water flows in the opposite direction. The direction of flow is reversed due to a change in pressure. When backflow occurs, contaminants can enter the drinking water system through cross-connections. Without the installation of a proper backflow device, something as useful as your garden hose has the potential to contaminate your home's water supply and the public water system.
A cross connection is a temporary or permanent connection between the drinking water system and any source containing non-potable water.
A potentially hazardous cross-connection occurs every time someone uses a garden hose sprayer to apply fertilizer or herbicides to their lawn. Without a backflow prevention device between the hose and the spigot, the contents of the hose and anything it is connected to can backflow into the home's water system and contaminate the drinking water. Backflow can also occur when the public water supply pressure drops or when the intended destination pressure is greater than the supply pressure.
The most effective method to prevent cross connection is the physical inspection of water piping during installation. Another method to prevent cross connection is the installation of backflow devices between the public water supply and the customer's establishment or residence.
Backflow devices include:
With the exception of the Hose Bibb Vacuum Breaker, city ordinance and the Florida Department of Environmental Protection require annual testing of backflow devices.