What do “cross connection” and “backflow” mean?

A cross connection is a connection between a potable drinking water pipe and a non-potable source. For example: you’re planning to spray weed killer on your lawn. You hook up your hose to the faucet on your house and to the sprayer containing the weed killer. If the water pressure drops at the same time you turn on the hose, the pressure change may cause the chemical in the sprayer to be sucked back into your home’s plumbing system through the hose. This is called backflow and could contaminate the water in your home system.

Water utilities deal with this issue on a much larger scale – imagine if your hose were connect to a fire hydrant or a public access faucet (e.g. a campground), then the weed killer would be sucked into the public water supply. Backflow from customer service connections is of concern to water utilities, and has been shown to occur in 1.6% of all meter reads and in 5% of homes with backflow-sensing meters.

Protecting the public water supply from contamination.

Cross Connection contamination of the public water supply is the leading cause of waterborne disease in public water systems. It can occur when any fluid or gas that is contaminated is introduced into the public water supply. Anywhere in the public or customer water lines where this can occur is considered a “cross connection.” Clackamas River Water is mandated by the State of Oregon Drinking Water Rules to eliminate or control all cross connections.

Cross connections can include garden hoses left submerged in buckets, hose-end chemical spray attachments, including pump type garden sprayers, lawn sprinkler systems, fire sprinkler systems, and auxiliary private water systems to name just a few. Cross Connections are controlled by the installation and annual testing of backflow prevention assemblies.

Backflow prevention assemblies are devices that can be installed in your water system to prevent water from flowing back into the public water supply. Backflow prevention assemblies are required by Oregon law to be tested at least annually by a State certified tester. If you know of backflow prevention assemblies at your property, be sure to have them tested.  For a CRW list of testers, click here.

Who to contact for more Cross Connection Control information

To learn more about the cross connection contamination safety of your home or commercial building, or about the required annual testing, contact Clackamas River Water's cross connection specialist by email at or call 503-723-2577.

For general information regarding cross connection visit: Oregon Health Authority Backflow Prevention Web Site

Listed below are links to helpful information that may assist your efforts to comply with both CRW and State backflow prevention requirements.  Your cooperation in helping keep our public water supply safe is greatly appreciated.