Whether I am working with a personal training client or teaching aerobics classes, it seems that almost every participant in the gym these days has a water bottle. Despite the fact that the gym has several strategically placed drinking fountains, with refreshingly cold water I might add, the majority of folks these days prefer to drink water out of a plastic bottle. Is this a matter of convenience, taste preference, or the belief that bottled water is somehow “healthier”? 

If the answer is this last one, we are all in for a surprise. In a recent 4-year review that included the testing of 1,000 bottles of water, the Natural Resources Defense Council-one the country’s most ardent environmental crusaders-found that “about 22 % of the brands we tested contained, in at least one sample, chemical contaminants at levels above strict state health limits.” As if that was not enough of a concern, the waters get even murkier (okay, you got me: pun intended!). While the presence of words on the bottle labels such as “pure”, “natural” and “pristine” may evoke the promise of bacteria-free hydration, it seems that approximately 25% of all bottled water is actually taken directly from municipal water sources.

The water inside the bottle might not be the only culprit, either. When certain plastics (among them, those used to make designer bottled water) are heated at high temperatures, chemicals byproducts may leach into container’s contents. While there has been much speculation as to whether the amounts of these chemicals are actually harmful, it seems that small amounts of toxic chemicals can in fact accumulate the longer bottled water is stored in a hot environment, such as a garage.

Certainly the fashionable BPA-free aluminum-type canisters are a great choice for toting around your favorite beverage while exercising, as they have been demonstrated to provide little if any risk in terms of toxicity. However, it would seem prudent to fill those canisters with tap water instead of the trendy, costly bottled variety. While you are treating your muscles to a vigorous workout, be sure to treat your insides as well.

Cathleen Kronemer, NSCA-CPT, is a longtime fitness instructor at the Jewish Community Center.