The U.S. Environmental Protection Agency has undertaken the development of a series of reports identifying specific deficiencies in the design of wastewater treatment facilities and presenting corrective solutions to avoid the error or to solve the problem. The report describes problems that are associated with organic overloading of Rotating Biological Contactor (RBC) units, presents an analysis of field data from RBC treatment plants identified as experiencing problems associated with organic overloading, and suggests design concerns that should be recognized in order to avoid RBC organic overloading and its associated process performance and equipment problems. Any one of a range of organic loading values for design may be used, the magnitude of which depends upon the risk of failure that the designer is willing to assume.