Backflow Prevention History - Case Study

Bangor, Maine, water department employees discovered poisonous anti-freeze in a homeowner's heating system and potable water supply in November, 1981.  The incident occurred when they shut off the potable water service to the home to make repairs.  With the flow of water to the house cut off, pressure in the lines in the house dropped and the anti-freeze, placed in the heating system to prevent freeze-up of an unused hot water heating system, drained out of the heating system into the house water lines and flowed out to the street.  If it had not been noticed, it would have entered the homeowner's drinking water when the water pressure was restored.

~Information obtained from the Backflow Prevention Reference Manual 2nd Edition IAPMO~