Don't buy bottled water on the assumption that it's safer or purer. From a safety and purity point of view, tap water stands up when compared to bottled water. If they haven't sent it, they will upon request. Neither agency is noted for tough or effective regulation. But they do provide some assurance of quality and safety.
Bottled water is often superior in taste when compared to tap water.
But, of course, there are all kinds of bottled waters and you have to be the final judge of taste. But others are more sensitive to taste variations so they have to hunt for the water that tastes best to them. Dannon was second according to their tasters, at about half the price of Volvic. The material of the container is an important determinant of the taste of bottled water. There are four kinds of containers.