With the increasing attention to environmental aspects of water quality, interest has developed in the feasibility of using controlled environment facilities in this research. Such facilities may make possible acceleration of important developments, whether the research relates to special variables under controlled conditions, or whether the need is to simulate a natural complex consistently over a period of time. Design requirements of controlled facilities must be approached thoughfully to achieve the desired results. Accordingly the Division of Water Supply and Pollution Control, Research Branch, enlisted the services of the author to survey some of the facilities of this type available in the United States. The present report summarizes his notes and observations.