France is considered as the cradle of ozonation with tests of water disinfection beginning in 1886. By 1961, over 500 ozonation plants were in operation in France, particularly for drinking water. In the past ten years, significant improvements in ozone generation have been made. Improvements in contacting systems include static mixers and radial diffusers. Advanced oxidation processes have been developed for new applications. In drinking water treatment, the ozone treatment has been moved from post-ozonation to an interozonation step upstream of a granular activated carbon (GAC) filter.