FEDERAL AND STATE LAW REQUIRES ALL PUBLIC WATER SUPPLY SYSTEMS TO PROTECT THE WATER SUPPLY FROM POTENTIAL CONTAMINATION OR POLLUTION. CONTAMINATION CAN OCCUR WHEN A WATER SUPPLY LINE TO A CUSTOMER IS CONNECTED TO EQUIPMENT CONTAINING A SUBSTANCE NOT FIT FOR DRINKING. THESE CONNECTIONS ARE CALLED CROSS-CONNECTIONS. IN ORDER TO PREVENT CONTAMINATION OF SUPPLY LINES FROM THESE CROSS-CONNECTIONS, THE PUBLIC WATER SUPPLY COMPANIES HAVE DEVELOPED AND IMPLEMENTED AN ORDINANCE WHICH REQUIRES ALL INDUSTRIAL, COMMERCIAL, AND IRRIGATION CUSTOMERS TO OBTAIN A BACK-FLOW PERMIT AND INSTALL BACK-FLOW PREVENTION ASSEMBLIES.
NCDENER ( NORTH CAROLINA OF DEPARTMENT OF NATURAL RESOURCES ) HAS CLASSIFIED ALL IRRIGATION SYSTEMS AS HIGH HAZARDS. ACCORDING TO DENER REQUIRMENTS ALL IRRIGATION SYSTEMS MUST HAVE AN RPZ ( REDUCED PRESSURE ZONE ) BACK-FLOW INSTALLED AND TESTED ANNUALLY BY A CERTIFIED BACK-FLOW TESTER.