From Forbes' Investopedia:

Bottled water sales had experienced rapid growth for more than a decade, as consumers embraced water over soda and other high-calorie beverages. Growth rates have slowed in recent years, due to market saturation, and have taken a more recent tumble on environmental concerns that millions of plastic bottles enter landfills every day, as only a small proportion of them ever reach recycling bins. Plus, why ship water across the globe when it can be affordable when consumed from a local tap?

Concerns About Tap Water
A shift back to bottled water may take place soon, because a recent New York Times study detailed that "more than 20% of the nation's water treatment systems have violated key provisions of the Safe Drinking Water Act over the last five years." It also relayed that "since 2004, the water provided to more than 49 million people has contained illegal concentrations of chemicals like arsenic or radioactive substances like uranium, as well as dangerous bacteria often found in sewage."