AWWA M46 : 2026

RO was commercialized in the United States in the 1960s and has been used for water desalting applications ever since. Through research and development, NF was shown to be a membrane process with lower operating costs for softening water and removing organic substances (color, disinfection byproduct precursors, and synthetic organics) for waters not requiring demineralization/desalination.

Membrane technology of all types became particularly applicable to drinking water production in the late 1980s when the amendments to the US Environmental Protection Agency’s Safe Drinking Water Act (SDWA) required higher-quality drinking water. The amendments were based on the latest research on health effects and the ability to detect contaminants at increasingly lower detection limits using sensitive analytical techniques. Because of their ability to remove or reduce many of the substances regulated by SDWA, membranes play an increasingly important role in enabling water utilities to meet these regulations.

This manual was developed to provide an overview of NF and RO technology for operators, administrators, engineers, scientists, educators, and anyone seeking an introduction to these processes. An introductory chapter, which discusses an overview of NF and RO processes and applications, is followed by chapters discussing NF and RO process design, facility design, residuals management, and operations and maintenance. The information contained in these chapters includes history, regulations, theory, terminology, water resources, pretreatment, process technology, posttreatment, concentrate disposal, and membrane and system components, configuration, maintenance, chemistry, cost, and safety. The final chapters provide case studies of existing NF and RO facilities, as well as market trends that offer insights into the future of NF and RO technology and applications.