What are some differences between tap water and bottled water?

• type of disinfection treatment used: Municipal systems may use chlorine, chloramines, ozone, or ultraviolet light to kill disease-causing germs. On the other hand, water bottlers typically use ozonation or ultraviolet light, so they can avoid an aftertaste from chlorine. However, ozonation by-products and the plastic bottle itself may affect can also affect the water’s taste.
• •fluoridation: Tap water is usually treated with fluoride; most bottled water is not. The natural levels of fluoride in the water varies depending upon the water source.

 
Source(s):
Cornell Cooperative Extension: “Water Quality: Bottled Water”
EPA Water Health Series “Bottled Water Basics”