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Back-flow & Cross Connections

Updated: 12/2022


What is backflow?
Backflow occurs when water in a piping system flows opposite of the direction it should. Backflow can be caused by water pressure either pushing or pulling water flow in the opposite direction that it’s supposed to go. Backflow can be a public health concern when drinking water pipes are connected to other types of piping systems, such as a lawn irrigation system or a fire sprinkler system in a large building, or to other sources of water. When backflow occurs, chemicals, fertilizers, or other types of contaminants or pollutants can be pulled or pushed back into the drinking water system and show up at your or neighbors’ taps.

Who needs to install an approved backflow prevention assembly?
Property owners must install an approved backflow prevention assembly if there is a risk that backflow could happen on your premises. Even if there is a potential cross-connection risk identified on your property, you may be required to install an approved backflow prevention assembly on your water service. These installation requirements are from the Utah Department of Environmental Quality.

Understanding Cross Connections
If non-potable water were to come in contact with the public water supply, the drinking water system could become contaminated. A cross connection is an arrangement of piping that could allow undesirable water, sewage, or chemical solutions to enter the drinking (potable) water system as a result of backflow. Backflow is the reversal of normal flow in a system due to back siphonage or back pressure.

Examples of Cross Connections*

  • A faucet connected to a hose lying in a bucket of dirty water
  • A water pipe connected to a broiler treated with chemicals
  • A hose connection to a chemical solution aspirator to feed lawn/shrub herbicides, pesticides, and fertilizers.
  • Lawn irrigation systems
  • Chemically treated heating systems
  • Water softeners
  • Hose connections to a water outlet or laundry tub
  • Swimming pools
  • Solar heating systems
  • Private non-potable water supplies
  • Non-code, siphon-able, ball cock assemblies in toilets
  • Water-operated sump drain devices.

*This is an abbreviated list of potential cross connection hazards.