What is backflow testing, and why does Portland require it?

A backflow prevention assembly is a mechanical device installed on your water line — most often where an irrigation or sprinkler system connects to the household water supply — that keeps water from flowing backward into the public drinking water system. Without one, contaminated water (fertilizer, pesticides, standing water) could theoretically be pulled back into clean water lines under certain pressure conditions. That's the risk the assembly, and the annual test, exists to prevent.

Why it's required annually

Oregon law (OAR 333-061) requires backflow prevention assemblies to be tested at least once a year by a tester certified by the Oregon Health Authority (OHA). The property owner is responsible for scheduling the test, and the local water purveyor — in Portland's case, the Portland Water Bureau — is responsible for enforcing it.

Why you got a letter in the mail

Each spring, the Portland Water Bureau mails reminder letters to property owners whose records show an installed backflow assembly — typically because they have an irrigation system. According to the Bureau's own published guidance, it does not perform the test itself and does not recommend specific testing companies. Instead, it directs you to OHA's public list of certified testers and leaves scheduling up to you. That's the gap this site exists to close.

What actually happens during the test

A certified tester connects test equipment to your assembly, checks that its internal check valves and relief valve are holding pressure correctly, and submits a report to the water bureau, typically within a matter of days. Most residential tests take well under an hour. If the assembly fails, the tester will tell you what needs to be repaired or replaced before it can pass.

Sources: Portland Water Bureau — testing requirements, OHA cross-connection rules.