Saturday, June 25, 2022
June 25, 2022

Linkedin Pinterest

Energy Adviser: Test for water backflow


Few of our community connections are as personal as a shared drinking water supply.

That’s why water utility managers ask the public to do their part to make sure home connections prevent harmful backflow into the communal water system.

The Clark Public Utilities Water Utility and other water providers in the region go to great lengths to ensure water systems never draw water from outside the system back in from the end user’s tap, but accidents can happen. That’s why working backflow prevention devices at the user’s end are so important.

Backflow means water flowing in reverse of its intended direction. Rather than it being pushed out of a pipe, it’s drawn back in.

Backflow is rare and if there’s a risk it’s generally after a significant impact to the water system like a main break or an event that causes a sudden drop in pressure, like a large firefighting effort near your connection. Irrigation systems are the biggest concern because without a functioning backflow blocker, the system can draw in harmful lawn and garden chemicals.

“Working backflow prevention devices will prevent contamination,” said Gary St. John, water quality specialist at Clark Public Utilities. “Every irrigation, automatic lawn sprinkling system, or large dedicated fire suppression system should have backflow preventers installed, and inspected and tested at least once a year.”

Backflow prevention assembly testing is required by law. Clark Public Utilities recommends testing in the spring, just before their irrigation season begins. The test is quick and doesn’t cost much.

To help customers comply with the testing requirement, the utility keeps a list of backflow testers on that customers can access at their convenience. Tester participation on our list is voluntary and not a recommendation or warranty of any kind — but it is a helpful place to start.

The water utility also offers a convenient annual backflow testing program to Clark Public Utilities water customers. Every year a certified backflow assembly tester is contracted at a set rate to test every participants’ backflow device. To participate, call the utility’s dedicated backflow line at 360-992-8589.

Clark Public Utilities water customers who aren’t sure if they have a backflow assembly can call 360-992-3000. If there’s not a record of a backflow prevention device at your address, a serviceman can come to inspect the system.

“We can only check backflow status for our water service customers and many in Clark County have water service through cities so be sure to check with your specific water provider,” St. John said.

If your property doesn’t have an irrigation system, you probably don’t need to worry about backflow. Residential and most commercial plumbing fixtures have air gaps that stop backflow. Many lawn sprinkler systems also have devices called atmospheric vacuum breakers, or AVBs for short that create air gaps.

The garden hose is one place a homeowner could encounter backflow. Homes built before the 1990s that haven’t been plumbed might not have vacuum breaker-equipped hose spigots. Replacing those old spigots with modern ones will take care of the issue. But if that’s not an option, the hose should never be submerged after it’s been shut off.

Property owners often don’t realize they have a backflow prevention device.

“Many of our customers who either just moved here or just bought a new property had never heard of backflow prevention or backflow testing until we connected,” St. John said. “The way to know if you have a backflow preventer on your irrigation system is to look for an in-ground, green-lidded rectangular box near the water meter or close to the house. If you have a backflow assembly, it’ll be in there.”

Energy Adviser is written by Clark Public Utilities. Send questions to or to Energy Adviser, c/o Clark Public Utilities, P.O. Box 8900, Vancouver, WA 98688.


Support local journalism

Your tax-deductible donation to The Columbian’s Community Funded Journalism program will contribute to better local reporting on key issues, including homelessness, housing, transportation and the environment. Reporters will focus on narrative, investigative and data-driven storytelling.

Local journalism needs your help. It’s an essential part of a healthy community and a healthy democracy.

Community Funded Journalism logo