More and more water jurisdictions across the US are requiring the use of the RPZ
instead of the double check. RPZ valves offer better protection to the water supply. With this added protection comes the additional work of specifying and installing reduced pressure zone valves in a safe place. Over the years, we've learned most designers just aren’t aware the relief valve could dump large volumes of water into the building. And those that did were incorrectly assuming the drain installed below the valve would be sufficient. This lack of awareness puts the building at risk of flooding if the relief valve opens. Here's a simple infographic to help break down the RPZ valve problem.