Cross-Connections between water supplies and non-potable sources of contamination represent one of the most significant threats to health in the water supply industry.
Backflow is the reversal of water from its intended direction due to a pressure differential. It can occur anywhere that has a potential cross-connection in a water system, including: dishwashers, garbage disposals, toilets, shower heads, faucets, pools, lawn irrigation systems, fountains, and hoses.