Before studies on the removal of radioactive materials by the experimental water treatment plant were initiated, it was felt desirable to obtain information relative to the efficiency of the plant in treating raw waters. To obtain these data, a treatment plant was in continuous operation for the period July 18-20 and July 25-28, 1949. During these intervals, turbid waters were treated with alum and alkali, passed through the coagulation and sedimentation chambers, and filtered. Hourly samples were collected of the raw, mixed, settled, and filtered waters, and the pH, turbidity, and alkalinity were determined.