Section 608.1/Backflow Prevention
IPC 608 covers backflow prevention requirements that protect the potable water supply from contamination by cross-connections.
A means of backflow prevention must be provided at every point of use where a cross-connection could contaminate the potable water supply. The type of backflow preventer required depends on the degree of hazard: high-hazard connections (sewage, chemicals, medical gas) require a reduced pressure zone (RPZ) assembly, while low-hazard connections (irrigation, cooling towers) may use a double check valve assembly. An air gap is the most reliable method and is required at certain connections. Backflow preventers on the building supply must be accessible for testing and maintenance.
Why this section exists
Without backflow prevention, contaminated water from a non-potable source can be drawn back into the potable water system during a pressure drop (backsiphonage) or when the non-potable system is at higher pressure than the supply (backpressure). A single cross- connection can contaminate the water supply for an entire building or even the municipal system. Documented backflow incidents have caused serious illness and death.
What plan reviewers look for
Plan reviewers identify every cross-connection on the plumbing drawings: irrigation systems, boiler makeup, cooling towers, fire sprinkler chemical injection, laboratory sinks, janitor sinks with hose bibbs, and medical equipment. They verify that the correct type of backflow preventer is specified for the hazard level. They check that the building supply backflow preventer (if required by the water purveyor) is shown on the riser diagram.
Common violations
Related IPC requirements
Section 608.13 covers specific backflow preventer types. Section 608.16 covers connections to specific equipment types. Section 604 covers water supply sizing that must account for the pressure loss through backflow preventers. The local water purveyor may have additional requirements.