Washington State Water Distribution Manager (WDM) 1 Certification Practice Exam

When testing a new pipeline with a fire hydrant, you must prevent water from flowing back into the drinking water system during the test. Install a backflow protection device in the test connection, and the common choice for temporary hydrant testing is a double check valve assembly. This setup provides two independent checks and shutoff points, reliably preventing back-siphonage while you fill and pressurize the new line. An air release valve handles trapped air, not backflow protection; a pressure relief valve protects against overpressure but doesn’t stop backflow; and while any backflow device works, the double check valve is the standard, practical option for this testing scenario.