The water community faces increasingly stringent regulatory requirements as detection methods continue to advance, increasing the number of substances known to exist in water. Membrane processes are superior to other processes in several ways, as they can resolve complex and often conflicting requirements related to multi-contaminant regulations, can be combined with disinfection processes that do not add byproducts to water, and do not vary significantly from day to day with fluctuations in raw source quality, whereas conventional methods can be dynamic and user-dependent. This text introduces the fundamentals and describes the applications for membrane technologies in the production of drinking water.