The U.S. Public Health Service (USPHS) drinking water standards were first adopted in 1914 to regulate the quality of water supplied to the public by common carriers engaged in interstate traffic. In 1925, the standards were revised and limits were established for certain chemicals. Additional revisions were made in 1942 and again in 1946; the 1946 standards are currently under review by a committee having AWWA representation. In their present form, the standards provide two different types of chemical limits: maximum permissible limits for chemicals with known or suspected adverse physiologic effects; and, recommended permissible limits for chemicals that are generally nontoxic but have adverse qualities pertaining to color, staining, taste, and odor. In addition, there are alkalinity requirements to prevent over‐treatment of the water with chemicals. The physiologic and aesthetic significance of the present chemical limits in the USPHS drinking water standards are discussed, and certain significant chemicals are suggested for future addition to the standards.