Backflow protection and residential fire sprinklers

Abstract

Is backflow prevention necessary to prevent stagnant water in residential fire sprinklers from contaminating municipal supplies? The current risk of death or injury from fire is 11.1 times higher than the current risk of waterborne illness. An analysis was conducted to determine the possible overall public health effect if residential fire sprinklers are connected to municipal water supply systems. Risk‐versus‐benefit calculations associated with the installation of residential fire sprinkler systems with and without various levels of backflow prevention are presented. The degree of risk for waterborne illness would remain essentially unchanged from current conditions if residential sprinkler systems were installed with a simple check valve device, and the relative degree of risk from fire would be reduced from 11.1 to 5.8.

Economic Performance of Residential Fire Sprinkler Systems

“…A backflow preventer prevents mixing of the water in the sprinkler system with the domestic system. The mixing of water in the two systems could present a health hazard from waterborne disease [29]. 6 The addition of a backflow preventer increases the installation cost of the system, as well as requires a regular annual maintenance by a professional, costing in the neighborhood of $100-$200 [9].…”

Water suppliers and plumbers share backflow prevention responsibility

“…Hart et al (1993) concluded that for every million people protected by sprinkler systems, 8.2 people would become ill from systems without backflow preventers. If these conclusions are correct about sprinkler system black water, the uncirculated water in plumbing system fixtures and appliances that retain water is a much lower risk to the public health.…”