In a 2010 study published in the Journal of Sensory Studies, researchers asked people to rate the taste of six bottled mineral waters and six types of tap water. They found that, overall, bottled water didn’t perform any better than the stuff from the tap. The reason: It’s mineral concentration, not “water purity,” that influences flavor. The study’s participants preferred water with medium mineralization, which they described as “tasteless” and “cooler,” but whether it came from a bottle or the tap made little difference.

The Natural Resources Defense Council recently tested 1,000 bottles of water and discovered that about 22 percent of the brands in the study contained chemical contaminants at levels above state health limits. And in 2011, California State University researchers tested six brands of bottled water and found that while none contained more than the legal level of contaminates, all six exceeded California public health goals for arsenic. There’s also substantial research showing that when certain plastic bottles are heated at high temperatures, chemicals from the plastic can leach into a container’s contents (a good reason not to store cases of water in the garage this summer). The takeaway: Don’t let label jargon like “pure” and “natural” fool you. Unlike bottled water, tap water is subject to strict federal, state, and local guidelines, making it a safer beverage choice.

#3: It may be glorified tap water:  Exotic names and labels conjure up images of tropical waterfalls and mountaintop springs, but in reality, roughly 25 percent of all bottled water comes from municipal water sources. Coca-Cola’s Dasani, for example, is nothing but purified tap water with added minerals. And Pepsi’s Aquafina? Another bottle of city water. I don’t know about you, but if I’m going to be drinking tap water anyway, I’d rather save some cash and drink the free version.

Most water bottles are made of a plastic called polyethylene terepthalate, or PET. There are two problems with PET bottles. Problem 1: They take a boatload of crude oil to produce. University of Louisville researchers estimate that around 17 million barrels of oil are used each year to produce PET water bottles—a major reason why bottled water costs roughly four times as much as gasoline. Problem 2: We’re chucking our water bottles in the trash, instead of the recycling bin. According to the Container Recycling Institute, nearly 90 percent of the 30 billion PET water bottles we buy annually end up in landfills—a huge problem when you consider that PET bottles take from 400 to 1,000 years to decompose. The bottom line: We should all take a cue from environmentally conscious activists like the folks at the University of Vermont—which recently banned bottled-water sales on campus—and opt for the tap whenever possible.