Degree of hazard
The classification of a cross-connection by the severity of harm its contaminant could cause, typically as a health hazard or a non-health hazard.
Degree of hazard is the evaluation of what could actually enter the potable supply through a given cross-connection and how harmful it would be. Most programs group hazards into two broad categories. A high or health hazard involves substances that could cause illness or death, such as sewage, chemicals, or biologically contaminated water. A low or non-health hazard involves substances that would degrade the water aesthetically, affecting taste, odor, or color, without threatening health.
The classification matters because it drives every downstream decision: which device or assembly is acceptable, where it must be installed, and how strictly the connection is monitored. A connection to a lawn irrigation system, a commercial boiler with chemical treatment, and a plain water-only heating loop each present different risks and therefore justify different levels of protection. Assigning too low a classification leaves people exposed; assigning too high a classification imposes unnecessary cost and pressure loss.
Testers and property owners should know that the water purveyor or authority having jurisdiction usually makes the final hazard determination, often during a cross-connection survey. Conditions change, though. A tenant switching from storage to chemical processing, or an owner adding a well or a pump, can raise the hazard level of an existing connection. Reporting changes in water use to the purveyor keeps the protection matched to the real risk.
Related terms
| Cross-connection | Any actual or potential physical link between a potable water system and a source of contamination or pollution. |
| Containment vs. isolation | Two complementary protection strategies: containment protects the public main at the service connection, while isolation protects users inside the building at each hazard. |
| Reduced pressure principle assembly (RP) | A testable backflow prevention assembly using two independently acting check valves with a pressure differential relief valve between them, suitable for high hazard applications. |
| Water purveyor | The utility or organization that owns, operates, and supplies a public drinking water system and is responsible for the quality of water it delivers. |
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