Wet-pipe fire sprinklers and water quality

This article describes the results of an 18-month collaborative investigati on with 30 water purveyors that studied the effects on drinking water in di stribution mains. In water samples taken from a variety of commercial wet-p ipe fire sprinkler systems, water quality exceeded the primary standard for lead and cadmium and the secondary standards for iron, manganese, sulfate, color, odor, and total dissolved solids. In field-scale backflow simulatio ns of an average 3- min hydrant-flow test, about 100 gal (0.4 m(3)) of wate r backflowed from a wet-pipe fire sprinkler system when the check valve was caused to fail in the open position. The estimated relative risk of being seriously injured in nonresidential fires is 33 times as great as the incre ased of contracting a waterbone illness after backflow has occurred. Retrof itting existing Class 1 and Class 2 wet-pipe fire sprinkler systems that do not currently have backflow prevention assemblies would cost about $4.4-6. 0 billion nationwide and was deemed not cost-effective.