What has been found recently is that if you use ozone in water treatment, or in waste water treatment, you can remove many of those harmful chemicals that are getting to be pervasive in our water systems, the endocrine disrupters and the flame retardants and other things, which we know are toxic to some of the ecosystem, and probably to humans, although we're not too sure. Ozonization of either the water when it's treated in the water treatment plant will take out most of these chemicals, or ozonization in the waste water treatment will prevent them from getting into the environment in the first place.
On March 27th, 2014. See this statement in context.