Backflow: the reverse flow of a liquid into the potable water supply. The installation of a backflow preventer protects the water supply from contamination from this very serious condition.
Backpressure: pressure, higher than the supply measure, caused by a pump, elevated tank, boiler, or any other means that may cause backflow.
Backsiphonage: backflow caused by negative or reduce pressure in the supply piping.
Cross-Connection: a connection or a potential connection between any part of the potable water system and other environment containing substances in a manner that under any circumstances would allow such a substance to enter the potable water system.
Health Hazard: a cross-connection or potential cross-connection involving any substance that could, if introduced into the potable water supply, cause death, illness, or spread disease, or have a high probability of causing such effects.
Non-Health Hazard: a cross-connection or potential cross-connection involving any substance that generally would not be a health hazard but constitutes a nuisance or would be aesthetically objectionable, if introduced to the potable water supply