Thy Cup Overflows—or Does It? Firefighters and Hydration

Firefighter dehydration chart

By Todd LeDuc

Cardiovascular death continues to account for most on-duty firefighter deaths. A key component to the complex interplay that has been written about and described previously includes the role that hydration status and dehydration play in cardiovascular strain. There are many serious effects of dehydration, including decrease in core body temperature control, decreased heat tolerance time, decreased cardiac output with elevated heart rate, and reduced aerobic power and muscle endurance (1).  In that same publication , it was noted that following the essential functions of fighting fire, firefighters lost almost an additional one percent of total body weight from fluid loss.


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We often compare firefighters to tactical athletes and rightly so, given the metabolic and physical requirements of the functions they perform. However, when we compare dehydration risk to firefighters and athletes, it is a “tale of two cities.” Typically, athletic activity leads to somewhere between 8-16 oz. water loss per hour, whereas firefighters lose 50-70 oz. of sweat in 30-45 minutes. This is a five-fold increase in water loss that is occupationally related to firefighting. This revelation should come as no surprise to any firefighter aware of the fireground variables such as extreme outside temperatures, high radiant heat,  the heavy, non-breathable personal protective equipment designed for thermal protection, and the frequent lack of proper prehydration and maintenance of a health hydration status.

Dehydration can be fueled by alcohol, caffeine, and sugary drinks that may exacerbate the hydration deficit. Studies that have detailed many firefighters report to duty dehydrated underscore the importance of addressing this both on and off-duty. By the time your body has thirst, already one percent of body weight has been lost and you are already significantly dehydrated, making addressing the problem even more challenging. (Swaka & Pandolf, 1990) It is important to maintain hydration throughout the course of the day, both on duty and off. Drink plentiful amounts of water throughout the day, with 64 oz. at minimum (Casa et al, 2001), adjusting this for physical exertion and exercising to account for excess fluid loss and perspiration.

One easy way to measure where you are on the proper hydration status is the use of urine charts at the bathrooms within the stations and training facility bathrooms. (see below).

Firefighter dehydration chart

The failure to account for adequate hydration can be devastating. It is important to address such an easily managed risk factor before heat stress and sudden cardiac events occur.


Walker, Adam. Pope, Rodney. Schram, Ben. Gorey, Richard. Orr, Robin. “The Impact of Occupational Tasks on Firefighter Hydration During a Live Structural Fire.” Safety. June 2019.

Todd J. LeDuc, MS, CFO, FIFirE, retired after nearly 30 years as assistant fire chief of Broward County, Florida, an internationally accredited career metro department. He served as chief strategy officer for Life Scan Wellness Centers, a national provider of comprehensive physicals and early detection exams. He has served as a member of the International Association of Fire Chief’s Safety, Health & Survival Section for over a decade and is currently secretary of the section. He is a peer reviewer for both professional credentialing and agency accreditation. He is editor of Surviving the Fire Service (Fire Engineering Books) and serves on numerous advisory boards and publications. He can  be contacted at Todd.

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