The Importance of Backflow Prevention: Lessons from Real Incidents
Backflow prevention is a critical safety measure for protecting public water supplies from contamination. The following real-life cases illustrate the severe consequences of neglecting backflow prevention measures and highlight the importance of strict regulations and protective devices.

Case 1: Insecticide Contamination in New Jersey (May 1973)
In May 1973, residents in Marlboro Township, New Jersey, faced a dangerous contamination of their water supply due to a backflow incident. An extermination contractor, while diluting the toxic insecticide chlordane using a submerged hose, created an illegal cross-connection. A simultaneous water main break caused a negative pressure that siphoned the entire insecticide drum into the town’s water system. This incident emphasizes the danger of cross-connections and underscores the need for backflow prevention devices, such as check valves or vacuum breakers, on external hose connections.
Case 2: Poultry Farms and Virus Vaccine Contamination (February 1974)
In 1974, an alarming number of cross-connections were discovered in the poultry industry, creating a significant risk to the public water supply. Live virus vaccines, used to immunize poultry against disease, were fed into drinking water systems. A survey across 26 poultry farms uncovered over 13,000 cross-connections that could allow the pathogenic viruses, many harmful to humans, to flow back into the water supply. This case shows the essential need for backflow prevention devices to stop viruses from entering drinking water systems, particularly in agricultural settings.

Case 3: Chemical Contamination in a Fast-Food Chain (December 1974)
In December 1974, over 300 people in a North Carolina city were exposed to chemically contaminated soft drinks at a major fast-food chain. The source of the contamination was traced to a nearby fertilizer plant. A check valve failure on the plant’s boiler allowed harmful chemicals to backflow into the water supply, affecting the restaurant’s beverages. This case highlights the importance of functional backflow prevention systems and regular inspections, especially in industrial settings, to protect both businesses and public health.
Conclusion: Backflow Prevention is Essential
These cases underscore the critical importance of backflow prevention systems. Whether in residential areas, agriculture, or industrial settings, backflow prevention devices, such as check valves and vacuum breakers, must be properly installed and maintained. Without them, the risk of contamination is significant, posing dangers to public health and safety.