Backflow from non-potable sources to a potable water supply can occur if there is a sudden drop in the water pressure. There are many cases throughout the United States where unintended backflow took place and caused a hazardous condition to the rest of the water system.
There are many different types of backflow devices that can be used and choosing a device is based on the identified risk to the water system. One of the most common is the pressure vacuum breaker (PVB).
PVB’s are often used when a home has an irrigation system. The PVB consists of a check valve and an air inlet that is vented to the atmosphere. It is designed to allow water through and keep the air inlet closed during normal conditions. When the air pressure is greater than the water pressure, the vented chamber opens and breaks the suction effect of the low pressure, preventing the backflow of water.
PVB’s must be installed in a manner that will not subject the device to flooding, excessive heat or freezing.
All backflow devices should be tested on an annual basis by a certified technician to ensure protection of the community’s drinking water supply. Backflow devices are regulated by the Uniform Plumbing Code and should never be retrofitted as it renders the device invalid.