U.S. Air Force Airman Alex McClendon, 633rd Aerospace Medicine Squadron bioenvironmental engineering technician, walks toward the education center at Langley Air Force Base, Va., June 12, 2015. The education center and other buildings on base get their tap water checked monthly for continued compliance with Air Force Instruction for drinkable water. (U.S. Air Force photo by Airman 1st Class Devin S. Michaels/Released)