In military´s operations, water is essential for troop maintenance and the operation of the field hospital. Ozone plays an important role in water treatment, acting in taste and odor control, water color reduction, oxidation of compounds and water disinfection. The objective of this work is to investigate the physical-chemical and biological modifications of raw water, collected from four different sources, to understand the ozonation mechanism in waters with different characteristics. The results suggest the presence of different oxidative pathways, with better treatment efficiency found in DLK sample. The other samples showed less effectiveness in ozone´s action, possibly because they have an indirect oxidative profile, with greater destruction of ozone, due to the presence of ammonia or nitrate in the water sources.