Five subjects participated in a taste evaluation experiment using acetic acid stimuli of 15 mg/1 to 35 mg/1 in 5 mg/1 intervals, mixed in .2 M NaCl to simulate domestic water of various qualities. Two Ss also received stimuli of 4 mg/1 and 45 mg/1. The experiment used a signal detection procedure in which decision criteria were generated through the use of questions concerning intended use. The hypothesis tested was that evaluational criteria are independent of subjective taste intensity. The data did not disprove the hypothesis. One S performed as predicted by the theory, and the response patterns of the other four Ss can be explained by the theory. The conclusions reached were: (1) the signal detection paradigm is a valid device for the measurement of evaluational criteria, even though a complex experimental design is required, (2) individual differences are a major factor in the perception of taste, (3) experiential history influences the establishment of a decision rule, (4) people prefer some taste in their water, and (5) people can tolerate a lower quality of water for purposes other than ingestion than presently allowed.