Potable (clean, drinking) water flows under pressure through municipal water lines to homes and businesses. Backflow is the reverse flow of dirty water through clean water lines. This creates a condition with the potential for contaminated water entering the municipal water system, and can cause a serious health hazard.
How can backflow occur?
Backflow can occur two different ways, by back siphonage and back pressure.
Back siphonage: When there is a sudden reduction in the water pressure in the municipal system, such as during fire fighting or when a water main breaks, water flow can be reversed. This can create a suction effect, drawing potential contaminates into the potable water system.
Back pressure: Back pressure is created when pressure in a non potable system, such as increased pressure from a water pressure pump or increased temperature in boilers, exceeds the pressure in the municipal system supplying the water. This can force water to reverse direction of flow through the cross connection between the two systems. Potential contamination can then enter the potable water system.
What is backflow prevention?
The installation of various types of assemblies using an air gap, check valves, reduced pressure assemblies or vacuum breaker assemblies to prevent potential contaminates from flowing into the potable water (municipal) system.
Who is required to have backflow preventers?
Commercial and multi-family residences, as well as some single family residences are required to have backflow prevention assemblies on all potable water service connections. The most common reason single family residences are required to have a backflow preventer is due to the installation of irrigation systems or swimming pools. Most simple irrigation systems only require vacuum breaker type preventers. However, if you have rain water or gray water systems that include a pump, reclaimed water irrigation, or a private well, you may be required to have other types of preventers that require annual testing and certification by certified testers. The results of the tests must be sent to the municipal water company each year.
If you need more information about backflow and preventers, you can contact your municipal water company and they will be able to answer your questions. If you are a Tucson water customer, you can also go their web site at www.tucsonaz.gov/water for more information.
If you are having problems with an existing backflow preventer, need maintenance done or repairs made, or need a new preventer installed, call us. We will have one of our technicians evaluate the need, and take the actions that are required.