Ray L. Derby, Principle Sanitary Engineer of the Los Angeles Department of Water and Power, provides an introduction to this symposium on water quality standards, including a brief overview of the development of water quality standards beginning in 1914 with the U.S. Public Health Service (USPHS) and its standards for water used on interstate carriers such as railroads, buses, steamships, and, more recently, airplanes. Revisions of this standard are outlined, along with the USPHS recommendations in regard to sanitary engineering practices. Omar C. Hopkins, Deputy Chief of the Water Supply & Pollution Control Division, U.S. Public Health Service, and Oscar Gullans, Chief Filtration Engineer of the South District Filtration Plant, Chicago, Illinois, discuss revisions and recommendations to the USPHS Drinking Water Standards on the following topics: source and protection; bacteriologic quality; physical characteristics; radiologic quality; chemical characteristics; and, new substances. John R. Baylis, Engineer of Water Purification at the Chicago Department of Water & Sewers, discusses the need for a water quality standard, and as an adjunct, the need for standard methods for testing water quality. The Baylis turbidimeter is discussed, along with the importance of turbidity measurement, the current lack of highly educated chemists and bacteriologists in some water filtration plants, the urgent need for research, a grading system for utilities to promote efficiency, employee training courses, promotion and salary, the need for a performance guide, unfiltered surface water, and the practical value of USPHS limits. Elwood L. Bean, Chief of the Treatment Section of the Philadelphia Water Department, discusses the need for professional standards in addition to government standards, the inadequacy of USPHS standards, the functional objectives of standards, and topics of consideration for a standard. Lastly, Frank E. Maloney, Dean and Professor of Law at the University of Florida's College of Law in Gainesville, Florida, discusses enforceable legal effects of water quality standards. Maloney also discusses public health legislation, fluoridation litigation, liability for negligence, and liability for implied warranty.