The Water We Drink: What About Bottled Water?

As with tap water, where it comes from and how it’s processed are key.

By: Marshall Worsham

Is bottled water any better than tap water when it comes to the presence of endocrine-disrupting compounds? It’s hard to say. On its own, the water in some brands may be safer than tap water. The reason isn’t necessarily the sourcing—many bottlers draw their water from the same municipal supplies that are pumped through your tap, and several studies have found traces of pharmaceuticals and industrial compounds in underground artesian wells. The difference often is the treatment processes bottlers use. On the other hand, biologists have raised concerns that plastic bottles themselves may leach EDCs into water.

EDCs aren’t on the radar of most bottling companies or of the Food and Drug Administration, which is responsible for regulating the sourcing and production of bottled water. Current laws require water to be free of contaminants above specified concentrations.

Most contaminants are prohibited not because they might interfere with the endocrine system but because they can be toxic in other ways. Some, such as arsenic, lead, and mercury, are familiar. Others—including the banned pesticide chlordane; benzo(a)pyrene, found in coal tar and automobile exhaust; and styrene, widely used in plastics—are suspected carcinogens. They are also suspected EDCs.

The FDA requires that bottlers test source water weekly for microbiological contaminants but only once a year for chemical contaminants. The agency also monitors processing plants. According to FDA spokesman Curtis Allen, because bottled water has a good safety record, “bottled-water plants generally are assigned low priority for inspection.”

This could change if EDCs prove to be a bigger public-health threat than lawmakers currently believe.

As far as water treatment goes, Allen explains, “Some of the technologies used by some bottlers may affect levels of EDCs, such as reverse-osmosis or activated-carbon treatment, but we do not assess the efficacy of these technologies.”

Major bottlers are similarly noncommittal with respect to EDCs. A spokesperson for the Coca-Cola Company, which sold 490 million gallons of its flagship water label, Dasani, in 2011, declined to comment on whether the company tests for EDCs specifically—or for any contaminants beyond those required by the FDA.

Is Dasani safer? Maybe. Coca-Cola gets water for Dasani primarily from municipal supplies—around here, that means the Potomac River—and from underground wells. Depending on how the source water has been treated beforehand, it may be processed through a granular-activated-carbon filter. After that, the water goes through a reverse-osmosis membrane to remove micro-compounds and is disinfected with UV light. The bottler adds minerals and then subjects the product to ozone treatment for final disinfection.

Two of the steps in Dasani’s treatment process—activated-carbon filtration and reverse osmosis—may remove substantial quantities of EDCs. According to a 2009 study, reverse-osmosis membranes and granular activated carbon each removed nearly 90 percent of EDCs and pharmaceuticals dissolved in tested water samples.

Thomas Zoeller, a biology professor at the University of Massachusetts-Amherst whose research focuses on molecular and developmental endocrinology, agrees that “reverse osmosis is perhaps the most stringent way to rid water of trace amounts of chemicals.”

Another potential problem with bottled water is the bottle.

Most containers sold commercially are made from polyethylene terephthalate (PET), a plastic compound generally thought to be safe. But more than a dozen articles published in the last five years have shown that phthalates and other EDCs appeared in concentrations up to 12 times higher in water stored in PET containers than in glass containers. Another popular plastic used in large water-delivery bottles, polycarbonate, is usually made with bisphenol A (BPA), a compound with suspected endocrine-disrupting properties. Over time, BPA seeps out of the plastic and into the liquid inside.

So are you better off drinking bottled water? Below is a list of seven major brands—along with their sources, whether they employ reverse-osmosis and activated-carbon filtration, and their packaging material—to help you decide.

Deer Park
Nestlé Pure Life
Poland Spring
Parent Company PepsiCo Coca-Cola Company Nestlé Danone Waters of America Roll Global Nestlé Nestlé
Source Municipal water Municipal water or protected ground water spring Alpine spring Artesian aquifer Municipal water or aquifer spring
Reverse Osmosis? Yes Yes No No No Yes No
Activated-Carbon Filtration? Yes Yes No No No Yes (for municipal) No
Packaging Material PET PET PET or poly-
PET PET or poly-
PET PET or poly-

Go back to What's In the Water We Drink?

This article appears in the July 2012 issue of The Washingtonian.