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Backflow Prevention Device

A backflow preventer is installed in a water system between the water supply and where the water is intended for use. Its job is to close a valve and prevent water from moving or seeping back to where it came from when the end of the flow is closed. In this sense, it stops the back-siphon that’s created when water is shut off. The backflow preventer keeps contaminated or polluted water from re-entering the water supply as it reverses direction from yards, pools, etc.

The biggest concern that backflow prevention addresses is keeping the drinkable water supply (potable) from being contaminated. Backflow preventers are used primarily in irrigation and sprinkler systems around your house where toxic fertilizers, chemicals and pet waste can exist. (See photos)

It’s also used widely in recent years on the main water infeed from the street where city water comes in. These devices contain a check valve that essentially only allows water to travel in one direction, and never backwards.

  • After the install or replacement of a backflow preventer, the device should be tested regularly (most models have test ports), to ensure it is work properly
  • Be sure to bleed residential backflow preventers in harsh winter climates to avoid freezing
  • Backflow valves come in plastic and metal models with all-metal devices being more reliable and meeting code standards regardless of water pressure

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