Bottled water has no advantages over tap water in areas with a potable water supply. It is a sound option for areas in which water is either scarce or untreated, making it unsafe to drink, says National Geographic.
In the United States, tap water purity is regulated by federal law. Companies producing bottled water obtain the water from public sources without observing the same purification processes. Bottled water can even contain dangerous, possibly carcinogenic, chemicals that escape from plastic bottles when the bottles are recycled and refilled, depending on what type of plastic the manufacturer uses, according to National Geographic.