What are backflow prevention devices and what do they do? Good question. Backflows are found in all commercial buildings, restaurants, and medical facilities. These devices are designed to contain all chemicals, whether food grade or of the cleaning kind as well as any blood borne contaminates. These devices (backflow preventors) are installed and inspected annually to ensure that our city’s water supply stays clean and safe to consume.
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What is a Cross-Connection?
Any physical or potential connection between a potable water supply and a hazardous material or one of questionable quality. City code states there shall be no such connection without the installation of an approved backflow prevention assembly in accordance to the degree of hazard of the substance involve.
What is Backflow?
Backflow is the undesirable reversal of flow of non-potable (undrinkable) water or other substances through a cross-connection and into the piping of a public water system or consumer’s potable water system. There are two types of backflow–back pressure and back siphonage.
What is Back-Pressure Backflow?
Back-Pressure backflow is backflow caused by a downstream pressure that is greater than the upstream or supply pressure in a public water system or consumer’s potable water system. Back pressure (i.e., downstream pressure that is greater than the potable water supply pressure) can result from an increase in downstream pressure, a reduction in the potable water supply pressure, or a combination of both. Increases in downstream pressure can be created by pumps, temperature increases in boilers, etc. Reductions in potable water supply pressure occur whenever the amount of water being used exceeds that amount of water being supplied, such as during water line flushing, fire fighting, or breaks in water mains.
What is Back-Siphonage?
Back-Siphonage is backflow caused by a negative pressure (i.e., a vacuum or partial vacuum) in a public water system or consumer’s potable water system. The effect is similar to drinking water through a straw. Back siphonage can occur when there is a stoppage of water supply due to nearby fire fighting, a break in a water main, etc.