Written by: Emily Joswiak • May 18, 2023• Home

A Brief and Interesting History of Backflow Prevention

Backflow preventers are crucial plumbing devices that protect the public from contaminated water supplies. Learn about the history of backflow prevention.

Did you know that, before 1974, unprotected plumbing cross-connection was entirely legal? Read on to learn a brief and interesting history of backflow prevention,the basics of backflow prevention, and the future of backflow preventer technology.

What Is Backflow Prevention?

Backflow prevention involves specific devices—conveniently named backflow preventers—to stop pollution and contamination caused by backflowing pipeline conditions from compromising potable water supplies. Normal plumbing conditions maintain a particular flow of water direction, with the help of pressure.

However, interruptions to this pressure can cause water to flow backward and re-enter public drinking water. Thankfully, pressure-sensitive backflow preventers monitor pipeline conditions and activate shut-off valves during backflow episodes, effectively protecting cross-connections.

The First Backflow Preventers

The very first backflow preventers were developed and implemented throughout Los Angeles in the 1930s. These devices featured a pressure vacuum breaker (PVB) assembly, a common design for modern backflow preventers today!

Despite the invention of PVBs, the widespread use of backflow preventers in American cities didn’t become more prevalent for many decades. However, following multiple backflow-related tragedies (most prominently the 1933 Amoebic Dystenty outbreak at the World’s Fair in Chicago), many large municipalities began implementing PVBs and related equipment into their plumbing systems. And in 1974, the Safe Drinking Water Act was passed into law and mandated that all unprotected cross-connections be eliminated or protected with a backflow prevention device.

Since the 70s, potable water supply laws and regulations have only become more effective and stringent. More importantly, backflow preventer technology is better than ever in human history!

Current and Future Outlooks

Along with the aforementioned PVBs, the most common modern backflow preventer designs are double-check valve assemblies (DCVA) and reduced pressure zone (RPZ) assemblies. However, both DCVAs and RPZs feature superior protections for cross-connections and vulnerable plumbing infrastructure. For example, DCVAs feature an additional check valve and chamber to ensure accurate shut-off responses to backflowing conditions.

Alternatively, RPZs often boast a pressure sensing line and bypass relief valve to effectively combat high-hazard plumbing systems (chemical processing plants and hospitals, for example). But where will backflow preventer technology go from here?

Most industry experts believe advancements in reliability, performance, and materials are the most likely improvements over the next few decades. For instance, 100-percent stainless steel backflow preventers are quickly replacing less-durable devices.

This brief and interesting history of backflow prevention highlights the importance of these devices within our society. Ensure your property or business has the correct backflow prevention equipment in place to protect your community from water-related complications effectively.

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Last modified: May 18, 2023