Protecting the City of Glendale’s water supply from contamination is important to all of our citizens.  To prevent cross connections to the cities water system the Arizona Department of Environmental Quality has adopted drinking water regulations, which require most commercial and industrial water customers to install and maintain backflow prevention assemblies. The backflow prevention assembly prevents contaminants from flowing back into the City’s public drinking water system once the water is delivered to the water customer. Each assembly installation must comply with the Glendale Standard Installation Detail.  A backflow permit and inspection is required for the installation of each assembly.  Water customers are responsible for installing, maintaining, and annual certification of each device.  After installation , each assembly must be tested by a certified backflow prevention assembly tester. All commercial properties built prior to 1991 must be brought into compliance. (R18-4-115)