Studies were conducted to evaluate several coagulation testing techniques. Of those considered, the jar-test was the most useful for evaluating the settleability of flocculated suspensions, and the membrane refiltration test for evaluating filtrability of a suspension. A jar-test procedure was then developed to provide more reproducible responses. Different velocity-gradient paths were examined for their effect on the overall efficiency of the flocculation process. The tapered velocity gradient path provided the greatest turbidity removal for settling periods of 30 minutes or more. For short settling periods (e.g., 5 min.), however, the step-up path was particularly useful. The effect of increased particle concentration on the agglomeration process was also studied. (Author)