What You Need to Know about Cross-Connections and Backflow

As spring approaches, many people are eager to begin participating in outdoor activities. But any outdoor activity that involves water – such as gardening, slip-n-slides, or washing the car – can increase the risk of a cross-connection or backflow. And that can create a dangerous situation where you could contaminate the drinking water supply for your home and your entire neighborhood.

What Is a Cross-Connection?

A cross-connection is an actual or potential connection between a public drinking water system and any other source that could introduce pollutants and/or contaminants, such as chemicals, bacteria, pesticides or wastewater, into the drinking water.

Common Cross-Connections


  • Lawn irrigation systems
  • Hoses and hose bibs (spigots)
  • Secondary water sources, such as pressure irrigation


  • Carbonator for soda machine
  • Lawn irrigation systems
  • Chemical dispensers
  • Pressure washers
  • Fire sprinkling systems
  • What Is Backflow?

    Backflow is the reversal of flow from a residential or commercial water system back into the public drinking water system. A backflow incident could occur if the water system pressure decreases, or the customer’s water pressure is higher than the water system pressure. A backflow incident could carry pollutants or contaminants into our public drinking water supplies making them unsafe to use.

    The Plumbing Code and Utah Public Drinking Water Rules require that all cross connections be eliminated or protected against backflow by installing an approved backflow device or assembly that will ensure that no impurities or contaminants are introduced to the public drinking water supply.

    What Is Backpressure?

    Backpressure is caused when a private water system or piece of equipment’s pressure is greater than the incoming water supply’s pressure causing a reversal of flow.

    Common causes of backpressure:

    • Pumps
    • Pressurized irrigation
    • Elevation Differences

    Steam/Air Pressure

  • Back-siphonage is caused when there is a reduction in the water supply’s pressure which causes a sub-atmospheric pressure in the water system causing water to reverse in flow.

    Common causes of back-siphonage:

    • Broken water lines
    • Flushing of fire hydrants or firefighting activities
    • Inadequate piping size

    How to Prevent Backflow

    It is the property owner’s responsibility to install and maintain the devices needed to prevent cross-connections and backflow. WaterPro, like other public water systems, helps protect the public health by monitoring and inspecting backflow prevention systems in use by our commercial and residential customers.If you have any questions about backflow prevention, please contact a licensed plumbing contractor or contact our WaterPro backflow prevention specialist at backflow@waterpro.net.