Use of Ozone in Drinking Water Treatment: A Factor of Public Health W. J. Masschelein. Honorary president of IOA, Belgium. Ozone is now used since one century in drinking water treatment in Europe. First for bacterial disinfection, followed by taste and odor control, removal of iron manganese. An irreversible break- through came in the sixties when was shown that ozone, if properly applied inactivates enteroviruses which were a problem at that time. Later came the use of ozone as a factor able to promote biodegradability of dissolved organic substance, able to cope with parasites and alone or with synergic procedures with very refractory compounds like chlorinated pesticides. Parallel to this evolution of applications the technologies for generating and contacting ozone to water were constantly adapted. This contribution will focus on ozonation of drinking water as a public health factor. Source: 2nd International Symposium on Ozone Applications Havana, Cuba - Mach 24-26, 1997.