Waste streams in water plants can include water from a variety of treatment processes, but the majority is typically backwash water. Other streams may include thickener overflows, lagoon effluents, plant drains, and waste streams from mechanical solids dewatering equipment. Concerns about recycle from both the regulatory and public health viewpoint exist over whether finished water quality is negatively impacted. This paper outlines water quality criteria, study design, and approach to full scale recycle studies. The results of two full scale recycle stream evaluations (Baltimore, Maryland, and Orange Water and Sewer Authority, Chapel Hill, North Carolina) are discussed. These studies were conducted in order to develop a thorough understanding of the potential full scale water quality impacts, and obtain regulatory approvals for implementation of permanent process water recycle systems. Includes 2 references, tables, figures.