Quotes on this page were taken directly from an EPA document entitled Water Health Series – Bottled Water Basics:
One of the key taste differences between tap water and bottled water is due to how the water is disinfected. Tap water may be disinfected with chlorine, chloramine, ozone, or ultraviolet light to kill disease-causing germs. Water systems use these disinfectants cholorine and chloramine because they are effective and inexpensive, and they continue to disinfect as water travels through pipes to homes and businesses. Bottle water that is disinfected is typically disinfected using ozone or other technologes such as ultraviolet light or chlorine dioxide. Ozone is preferred by bottlers, though it is more expensive than chlorine, because it does not leave a taste and because bottlers do not need to worry about maintaining disinfectant in water sealed in a container. Untreated water, whether from a bottle or from a tap, will have the characteristic taste of its source.
It appears that ozone is an accepted method of disinfecting water. Pretty cool, huh?
The document also states the following:
Ozonation – water is disinfected using ozone, which kills most microbes, depending on dosage applied.
What does an ozone generator for liquids look like? :
