The City backflow program was created to protect the water within our distribution piping. Should low pressure within the water mains ever occur due to a fire event or breakage, backflow devices will prevent water from within houses and commercial buildings connected to those mains from flowing backwards into the system and causing contamination.
No one wants the water from the neighbors’ water heater or mop sink in the water main when the pressure is restored! Think also of commercial and industrial connections!
We can protect the quality of the water by ensuring backflow incidents do not occur!