In this article, the possible adverse health effects caused by human consumption of reused water are surveyed, and suggestions are outlined for laboratory animal tests to evaluate chemical constituents of the water. Specifically, animal assays are proposed for the acute, subchronic, chronic, neurologic, immunologic, teratogenic, and reproductive effects from exposure to concentrates of organic chemicals in finished drinking waters. Chemicals discussed in this article include organic and inorganic chemicals, suspended particulates, and radiochemicals. Special attention is given to the suspended particulate asbestos. Includes 14 references.