Characterized are some of the water resources of New Mexico in terms of quality for usage by ruminant and non-ruminant animals, to identify water resources with potential hazards to animal health, and to derive quantitative relationships of animal performance. Samples were analyzed chemically for major minerals and assayed for quality in terms of mouse growth, mouse reproduction, and degradation of fibrous substrates by rumen microorganisms cultured in vitro. The results indicate that the mouse is insensitive, in terms of growth and reproduction, to differences in quality of drinking water. It is suggested that certain major mineralized water resources of New Mexico may have greater potential for use in animal production than would be expected from standards of water quality currently used.