U.S Air Force Airman Alex McClendon, 633rd Aerospace Medicine Squadron bioenvironmental engineer technician, tests a water sample at Langley Air Force Base, Va., Feb. 9, 2016. Routine water samples are taken from various facilities across the base testing for chlorine, potential hydrogen and bacteriological matter in the water. (U.S. Air Force photo by Senior Airman Brittany E. N. Murphy)