Cross-Connection ControlIntermediate 20 min read

Cross-Connection Control: Process Control Basics

For Class 2 distribution operators: degree-of-hazard classification, the four core backflow prevention assemblies (DCVA, RPZ, PVB, AVB) and where each is required, and the basics of testing requirements and cross-connection surveys.

A double check valve assembly and a reduced pressure zone assembly can look almost identical sitting on a customer's service line — both have two gate valves, test cocks, and internal check valves — but installing the wrong one at the wrong connection can be the difference between a nuisance and a public health emergency. At the process control level, your job shifts from recognizing that a hazard exists to correctly classifying it and matching it to the assembly actually engineered to stop it. That match is built on one foundational concept: degree of hazard.

Degree of Hazard Classification: Health vs. Non-Health Hazards

Every identified cross-connection gets classified by the severity of what could happen if backflow occurred through it. The industry recognizes two broad categories:

Health hazard (high hazard). A condition where backflow of a substance could cause illne

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