This booklet presents the language used in dealing with water. The booklet is intended to provide decision-makers with an adequate base of information to analyze water sources for consumption, recreation, and industry. The first section defines water and its properties, geologic locations, domestic and industrial uses, and patterns of change. The second section discusses water-quantity terms in metric-English equivalents. Water-quality terms such as temperature, specific electrical conductance, pH, sediment, coliform count, and dissolved oxygen are presented in section 3. The final section contains a glossary of technical terms. The main emphasis is on terminology and equivalents with some discussion of theory. (MR)