What Is Backflow?
Most people think that water can only flow one way—from the water source to the tap. However, water can also flow in the reverse direction during certain hydraulic conditions, such as when a water main breaks, a pump fails, or a heating/cooling system builds up too much pressure.
When the water flow is reversed—even for a short period of time—the results can potentially be extremely serious, as non-potable water can infiltrate the drinking water supply. Public health risks may include waterborne diseases from such contaminants as E.coli, Salmonella, and Giardia, and exposure to toxic chemicals like pesticides, metals, and volatile organic compounds. This can potentially occur in both residential and industrial environments.
Contamination from Cross Connections
Equipment failure isn't the only backflow risk. A cross connection—any direct or indirect connection between a potable water system and any other liquid, gas, or solid matter-is a potential accident without backflow protection. For example, using an unprotected garden hose to flush the antifreeze from a car radiator can create a public health hazard should backflow occur. Fire suppression systems in old commercial buildings are also dangerous, as water often sits unused in the black iron piping for many years. All potentially hazardous cross connections should have proper backflow protection.
