The Backflow prevention devices have built-in ports which make testing easy. The device is tested by a plumber using a specially designed test kit. For your benefit, Everest Drain and Plumbing can provide the best customer experience; with an annual reminder to have your RPZ certified to stay in agreement with your city. In addition, you can reach us at 416-383-7378, we are available 24 hours for regular and emergency plumbing services.