Backflow Prevention and
Cross-Connection Control

Definitions

Air-Gap: A physical separation between the free flowing discharge end of a potable water supply pipeline and an open or non-pressure receiving vessel.

Approved Air-Gap: An air-gap gains approval by being at least double the diameter of the supply pipe measured vertically above the overflow rim of the vessel.

Backflow: Flow in a direction contrary to the normal or intended direction. The unintended flow of water from a potentially polluted source into a potable water supply.

Back pressure: The difference between the pressure within any water service and a higher pressure within any vessel or pipework to which it is connected. For example, a customer is using water at a higher pressure than the pressure supplied by SACWSD.

Backflow Prevention Device: A device to prevent backflow. There are a number of different devices including a reduced pressure zone device, a pressure vacuum breaker, a double-check device and a registered air gap.

Backflow Prevention Device Inspection and Maintenance Report: Form which backflow accredited plumber completes to certify the correct commissioning and function of the backflow device.

Backsiphonage: Backsiphonage occurs when the water supply pressure falls below atmospheric pressure.

Containment Device: A backflow prevention device installed at the water meter(s) on the property boundary, to prevent backflow from within the property.

Contaminant: Any solid, liquid or gas with potential to enter or pollute the potable water supply.

Cross Connection: see above

Double Check Valve Device: a device composed of two independently acting check valves, including tightly closing resilient seated shut-off valves attached at each end of the device and fitted with properly located resilient seated test cocks.

Isolation device: A backflow prevention device installed at the connection to specified sections of a plumbing system within a building or facility.

Non-potable Water: Water is deemed non-potable if there is potential for contamination from an unprotected source.

Pollutant: An impairment of the quality of the public potable water supply which does not create a hazard to the public health but which does adversely affect the aesthetic qualities of such potable waters for domestic use.

Potable Water: Water which is suitable for human consumption.

Pressure Vacuum Breaker: A device composed of an independently operating internally loaded check valve and an independently operating loaded air inlet valve. This unit also includes tightly closing resilient seated shut-off valves attached at each end of the device and properly located resilient seated test cocks.

Reduced Pressure Device: A device composed of two independently acting check valves together with a hydraulically operating, mechanically independent pressure differential relief valve located between the check valves. This unit also includes tightly closing resilient seated shut-off valves attached at each end of the device and properly located resilient seated test cocks.

Service Connection: The point of delivery from the public potable water system to the consumer (i.e., meter location).