Sanitary surveys have been completed in all participating countries indicating the sources of microbial pollution in the selected harvesting areas. Data from the sanitary surveys and initial sampling have been used to develop extensive monitoring programmes in the harvesting areas. In 2006, the first use of quantitative real-time PCR methods developed in the REFHEPA project 3.1 was performed on samples from the REDRISK sites (shellfish and water). We demonstrated the technique was rapid, easy to use and could be performed by partners after a short training period. Although the technique is being improved and finalised in the REFHEPA project it was possible to use the methods and strategies developed to determine the relative quantity of viruses found in shellfish. Using these procedures the REDRISK project has developed an increased understanding of the critical points at the origin of the viral contamination. Site-specific parameters, including hydrodynamics factors which are different from Mediterranean or Atlantic coast and especially marine dilution of fecal input play an important role on shellfish contamination. The results clearly demonstrate the role of the proximity of outfall to the shellfish beds, the effect of rainfall and raw sewage discharged during epidemic diseases in the population. Different models were established to predict various impacts (particle-tracking model and predictive model between rainfall and salinity). These results also provide the strong basis for establishing potential early warning systems in European shellfish production sites. Data obtained from the REDRISK project is being used to develop a Risk Matrix approach to assess the risk in sites. A strategy to manage risk is proposed based on the probability of risk occurrence of deteriorating events and the possible impact of fecal contamination leading to the presence of human viral pathogens in shellfish.