The backflow test tells us if the backflow assembly is operating properly. If it is not, there is a risk that reversal of water flow could endanger the public health. The backflow test doesn't tell us specifically the cause of the failure. To learn the cause (or causes) of the failure, we must disassemble the device and trouble-shoot. Sometimes the problems are obvious and sometimes they're not. Here are some pictures of what we find in the field.