Backflow - The reversal of normal flow of potable or non-potable water/other substances into a drinking water system (DWS) that may be caused by back-siphonage or back pressure in the presence of a cross-connection

Cross Connection - Any actual or potential connection between the waterworks & any source of pollution, contamination or other material/substance that could change the quality of water in a DWS

Backflow Prevention Device - One-way valves installed in plumbing systems to prevent “backflow” of potentially contaminated water/substance(s) into potable DWS

1. 1.                
      

   2.                   Three things must simultaneously happen: