UDOUT is an umbrella term for current work in the domain of uncertainty- and risk analysis for design and operation of wastewater treatment plants. modelEAU members are currently leading and managing an international task group (IWA/WEF) which is reviewing the "state of the art". Within a project financed by an NSERC-CRD grant, modelEAU members are developing a procedure for risk-based design of wastewater treatment plants. Other themes include influent generators, reliability analysis, and the study of legislative and decision-making aspects. The objective of UDOUT is to transition the wastewater profession from guideline-based design to probabilistic use of simulators, which will provide utilities with more effective facilities and increase the socio-economic benefits of water reclamation. The projects are financed by scientific funding agencies, engineering companies as well as utilities.