In a Paris suburb, raw water monitoring conducted since 2000 revealed the presence of Cryptosporidium. A risk assessment was conducted and established that the elimination of Cryptosporidium would not be sufficient while complying with the new bromate standards. Ultraviolet (UV) irradiation offers a cost-effective approach to achieve high disinfection and appeared to be an appropriate alternative for the disinfection of surface water. The question of where and how UV should be integrated in an existing water treatment train was discussed, combining disinfection byproduct impact on downstream processes and cost considerations. It was found that UV would meet the disinfection needs of Neuilly-sur-Marne SWTP without photolysis of pesticides, production of nitrates, or negative impact on downstream process. Results from pilot testing have shown that the best UV location for water quality and cost considerations would be after GAC filtration. LP or MP lamp technologies could be used and their impact on water quality appeared to be close but in France, the MP system has to be authorized by water authorities before implementation. A UV step will be implemented in the Neuilly-sur-Marne SWTP in 2008. Includes 17 references, tables, figures.