The purpose of a back flow preventer is to provide protection of the public from the possibility of contamination or pollution by isolating such contamination or pollutants which could back flow or back-siphon into a potable water supply.
Back Flow Preventers Required
Back flow preventers are required as follows:
Fire lines
Funeral homes
High rise buildings
Hospitals
Hotels
Motels
Restaurants
Rest homes
Yard sprinklers
All back flow preventers shall be tested when they are installed and every year thereafter.