Airmen 1st Class Lauren Allen and Spencer Hearn, 28th Medical Operations Squadron bioenvironmental engineer technicians, test drinking water on Ellsworth Air Force Base, S.D., Nov. 30, 2011. The hach water testing kit measures chlorine and PH levels in drinking water to ensure it’s safe for all Ellsworth families. (U.S. Air Force photo by Airman Alystria Maurer/Released)