There's a reason wine and spirits are stored in glass: purity of taste. Plastic (and, to a lesser degree, metal) can impart various "flavors" into the liquids it comes into contact with. But that's just one reason that glass is an increasingly popular alternative to plastic and aluminum or stainless steel sport-style bottles.
Another is peace of mind. About five years ago, scientists and the Food and Drug Administration started issuing warnings about bisphenol A, commonly called BPA, a chemical used in plastics and in the linings of some metal vessels. Then, in 2010, the FDA recommended that parents avoid using bottles and cups containing BPA when feeding infants. That warning was enough to prompt many plastic-bottle manufacturers to start making BPA-free bottles. And it motivated many consumers to look for alternatives for their older children and themselves.
"Glass is made from naturally abundant materials — primarily sand — and it won't degrade over time," says Scott Radcliffe, a spokesman for glass-bottle manufacturer Lifefactory, which is based in Sausalito, Calif. Plus, "glass can last for decades," he says.
The glass used for food and beverage containers doesn't leach chemicals, nor will using glass to hold beverages other than water — i.e. sports drinks — affect the material or absorb residual tastes or odors. Glass bottles are also safe to clean in a dishwasher, and it's easy to see when they are sufficiently clean — something that's not always clear with plastic or metal containers.
Of course, there's a downside: Glass is breakable. The glass used for sports beverage bottles is very durable, but many companies are adding an extra layer of protection by wrapping the bottles in protective silicone sleeves. Another downside is that glass bottles are more than twice as heavy as plastic or metal. While carrying a glass bottle to yoga or Zumba or stashing one in the cage of a bike is one thing, hikers might be wary of carrying such a load.