After maintaining this Fire system Backflow Preventer for years it was due to be replaced. Backflow Preventers are designed to prevent potential/non-potable water from mixing with potable water. In this case we are preventing the water in the fire sprinkler system from mixing with your drinking water. This applies to commercial buildings and residential housing. Residential systems are designed to prevent this cross-contamination from potential/ non-potable to potable water in systems such as fire sprinklers, dishwashers or clothes washers. Frequent Testing and Maintenance of your Backflow Preventer is highly recommended in order to maintain at its best, and to prolong the life of your backflow prevention system.