Pictured here is the Soldier Water Estimation Too app main screen. This Android-based smartphone application is a decision aid that translates a complex sweat prediction model into simple user inputs. (U.S. Army graphic)

Clean, potable water is one thing the world universally cannot live without. It hydrates. It cleans. It keeps us alive and well. That makes water very valuable to soldiers. However, as many mission planners know, water planning can be a nightmare. Too much water can strain already heavy combat loads, perhaps forcing some soldiers to pack too little in favor of a lighter pack. When soldiers don't have enough water, dehydration could set in, decreasing performance and increasing the risk of serious heat illnesses. To help solve this logistical problem, researchers from the U.S. Army Research Institute of Environmental Medicine’s (USARIEM) Thermal and Mountain Medicine Division and Massachusetts Institute of Technology’s Lincoln Laboratory worked to develop an app that will help unit leaders accurately predict water needs with the goal of minimizing the burden of water transport and sustaining hydration. The app is designed to satisfy the military’s desire for paperless guidance that is simple, accurate, mission-specific and available in real time.

Called the Soldier Water Estimation Tool, or SWET, this Android-based smartphone app is a decision aid that translates a complicated biophysical and physiological sweat prediction model into simple user inputs regarding the anticipated intensity of activity (low, medium, high, including example activities), three category choices of military clothing ensemble and weather conditions (air temperature, relative humidity and cloud cover). The SWET app has user-friendly inputs and provides the user with the amount of water required for the specified conditions in liters per hour. A separate "Mission Calculator" tab further simplifies planning by providing total amounts of water required for a given unit (number of people) for a given mission duration (total time, in hours). Total water amounts are provided in liters, one-quart canteens, two-quart canteens and gallons.

Project leader Dr. Nisha Charkoudian, a research physiologist from USARIEM, said this app was designed for unit leaders to determine group water needs. The average amount of water needed per person does not reflect individual differences, but the model error for individuals is estimated to be small. Soldiers should expect to see this app within the year on the Army's Nett Warrior platform. In the meantime, Charkoudian said that the app has already undergone limited user testing with the Army Mountain Warfare School in Jericho, Vermont, where soldiers gave very positive feedback. She is looking forward to more feedback once the app goes live, to make updates and possibly explore its uses in the commercial world.