increase in pressure in a consumer water system, or a branch, above the pressure at the service connection. Note: Back pressure generally is caused by pumps, thermal expansion, or reasons other than reduc­tion or loss of incoming pressure. It generally is more evident in a closed water system 

reverse flow in a water system caused by negative pressure in an incoming pipe, when the point of use is at atmospheric pressure. Note: Back-siphonage generally is more evident in an open water system 

reverse flow in a water system from the normal or intended direction. Note­: Backflow generally is more evident in an open water system 

device designed to prevent reverse flow in a water system. Note: Term normally used where back pres­sure-type backflow is implied.

program, ordinance, or code designed to prevent backflow into a potable water system; and to discover, to eliminate, to prevent all uncontrolled cross-connections, existing or potential 

person qualified and certified to test and to repair backflow-prevention devices, and who has proved competency to the applicable regula­tory agency(s).

person qualified and certi­fied to test, but not to repair, backflow-prevention devices, and who has proved competency to the applica­ble regulatory agency(s 

food deterioration caused by microorganisms 

chemical or physical agent capable of killing bacteria