The treatment objective of an ultraviolet disinfection system used in a wastewater application is to protect the aquatic environment and users of water that receive discharges from wastewater treatment plants. To ensure this objective is adequately met it is important to validate, or verify equipment performance for a specific application. The widely accepted method for completing this validation is by determining the UV dose delivery performance using biodosimetry. Until now a standard bioassay did not exist for UV equipment that is used to disinfect treated wastewater from a biological treatment plant that is achieving an average effluent quality of less than 30 mg/L BOD/TSS and disinfection requirements of 126 cfu/100 mL E. coli over a 30 day geometric mean or 200 cfu/100 mL fecal coliforms over a 30 day geometric mean. A uniform bioassay for wastewater UV equipment that can be widely adopted by industry and regulatory bodies was developed and approved by the International Ultraviolet Association. This bioassay for UV equipment is described.