What is the minimum nozzle flow rate required for mass decontamination showers?

• A. 50 GPM
• B. 100 GPM
• C. 175 GPM
• D. 225 GPM

Answer: (C)

Mass decontamination showers rely on delivering enough water volume to fully flood and rinse contaminants from exposed skin in a timely manner. The nozzle flow rate is the key control that determines how much water is available to create an effective blanket of washwater and to dilute and remove contaminants as people pass through the decon line. The minimum flow rate that meets standard requirements for a mass decon shower is 175 gallons per minute. This level provides sufficient water volume to achieve thorough coverage and rinsing within typical decon procedures. Flows around 50 GPM are too low to remove contaminants quickly; 100 GPM is still below the practical minimum; while 225 GPM would exceed the minimum, the question asks for the threshold that defines the minimum acceptable flow. In practice, multiple showers and higher total flow are common to handle several victims, but per nozzle, 175 GPM is the essential minimum.