Recently, director of EnviroDesign Management Randy Holland gave a presentation to the San Antonio chapter of the American Backflow Prevention Association. The presentation was recorded and you can now watch it and learn about backflow prevention best practices. This is the third video in a three part series. Click on these links to find the first video on cross connection control industry changes, and the second video on indoor installation of RPZ backflow preventers.
Here's the intro to this 7 minute segment........"When a backflow preventer is installed below grade the vault in the pit in which assembly is installed may fill up with water. The water in the pit could create a cross connection between the water in the pit and the backflow preventer through the test cock." Here's the money line: "This may occur whether the test cocks are opened or closed." How is that possible? Aspiration. You get a test cock on number one that's leaky even when it's closed because it's just ferreted out. Every time you have a backflow you're pushing contaminated water from that vault into the city water main. Every time you have the same kind of a valve on number four you're pushing water into the customer's water continually from the vault if you're aspirating. Watch the video below for more details on flooded vaults and the rest of the reasons why backflow installation should stay above ground.
You can also download the companion guide that covers this and other topics by clicking below.