RPZ backflow preventers are required for medical and restaraunt water systems in my state. I understand that they are supposed to prevent biologically or chemically contaminated water from backing up past the meter into the fresh water system.
What I want to know is, under what circumstances would that ever occur? It seems to me that the water pressure in the lines would not allow contamination to run backwards through the system. Would the plumbing of the building have to be completely under water for this to ever happen?
I realize this isn't the 'plumbing' section, but if there is a plumbing section, I couldn't find it!
Tags: