Backflow Devices
A back flow preventer is a check valve that prevents water from flowing backwards into a water supply line resulting in a contaminated water supply. There are degrees of protection ranging from a vacuum breaker on a garden hose line to reduced pressure zone backflow preventers commonly used in a n industrial setting where chemicals are connected to water lines and if pressure was lost on the water supply cross contamination could occur. What is used and where it is installed depends on the application and the treat level.
Back pressure is another way that an unwanted contaminant may enter your drinkable water piping. Sources of back pressure may be pumps in the water supply system, boilers or heat exchanging equipment and even power washing equipment. In these cases you may have an almost constant risk of overcoming the static water pressure in the piping and when chemicals are used, as they are for commercial/industrial boilers or residentially as in deck/siding cleaning such as bleaches (power washing), you would benefit greatly from having a backflow preventer.
To prevent such an occurrence, many regulatory branches require there to be an air gap or automatic backflow prevention assembly between the delivery point of mains water and local storage or us [Where submerged mains inflow is permitted a backflow prevention assembly is required. In this way the backflow prevention assembly protects the potable water system from contamination hazards which can be severe. There are over 10,000 reported cases of backflow contamination each year. Some cases can be fatal.
