Section 760.970  Backflow

The potable water system shall be installed to preclude the possibility of backflow.  Devices shall be installed to protect against backflow and backsiphonage at all fixtures and equipment where an air gap at least twice the diameter of the water system inlet is not provided between the water supply inlet and the fixture's flood level rim.  No hose shall be attached to a faucet that is not equipped with a backflow prevention device.