Many ozone was added to water, do you know reason of it? Because of its excellent disinfection and oxidation qualities, ozone is widely used for drinking water treatment. 
It have these functions at water purification process:
1.Remove organic and inorganic matter and micro-pollutants
Ozone is the same as othe oxidant, it is difficult to get the oxidation to a fully mineralized state. But when the orgnic was oxidated by ozone that will be more easily biodegradable. And when ozone is used together with a coagulant, it can remove more material. After ozonation, you have to filter the organic.
Micro- pollutants such as pesticides may occur in surface water, but also increasingly in groundwater.Many research shows ozone can remove micro-pullotants.
2.Enhanced disinfection and readuce byproducts.
Many chemical(chlorine, chloramines, chlorine dioxide ect.) will leave some material and produce byproducts by water purification, such as bad smell, colors, solid particles and so on.  Ozone is a more effective disinfectant than chlorine, chloramines, and even chlorine dioxide. It will not leave any material in water, you only need to wait a few minutes or hours, you can get clean water.
Maybe you can’t believe ozonated that’s no promble and you can check more information about ozone. I think you will get the same conclusion as me.