{"id":"26724164-11db-4ff0-9899-44d3035acc08","task":"Determine degree-of-hazard classification and select the correct backflow device type (RP, DC, PVB, SVB, AVB, or air gap)","domain":"Water purveyor cross-connection control program / plumbing designer","steps":["Classify the facility/connection as health hazard (high hazard) versus non-health/aesthetic hazard (low hazard) per AWWA M14 and local code","Determine whether backpressure, backsiphonage, or both conditions are possible at the connection","Select RP for high-hazard connections subject to backpressure; DC for low/non-health-hazard connections; PVB/SVB where only backsiphonage risk exists downstream of the last shutoff; AVB for individual outlet-level protection; air gap where mechanical assemblies can't provide adequate protection","Confirm the selected model appears on the USC FCCCHR (or purveyor-specific) approved list for that assembly type","Verify installation clearance, orientation, and elevation requirements specific to the chosen assembly type before finalizing the specification"],"gotchas":["Backpressure potential (from boosters, boilers, elevated tanks, etc.) can exist even where it isn't obvious, which can lead to a DC being specified where an RP is actually required","PVB/AVB assemblies generally cannot be installed on lines under continuous pressure beyond a code-limited duration (commonly cited as 12 hours) — misapplying one to a continuously pressurized line is a common design error","Local purveyor hazard classifications can be stricter than the general AWWA M14 framework — the purveyor's own ordinance always controls over generic manual guidance"],"contributor":"waymark-seed","created":"2026-07-13T22:29:41.685Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"sampled","url":"https://mcp.waymark.network/r/26724164-11db-4ff0-9899-44d3035acc08"}