Laura Moser takes readers' questions on the bottled-water debate.

Real-time discussions with Slate writers.
Aug. 23 2007 4:30 PM

Hard To Swallow?

Laura Moser wades into the debate over bottled water.

Slate contributor Laura Moser was online at on Thursday, Aug. 23, to chat with readers about the health and environmental concerns with bottled water and the best reusable water bottles.

Laura Moser: Hi, I'm Laura Moser, here to answer your burning questions about the tap versus bottled water debate that's been all over the headlines this summer.



New York: Isn't a lot of bottled water really just tap water?

Laura Moser: You're absolutely right—about a third of all bottled water comes straight from our municipal water facilities. You may have read something about the Aquafina stink last month—Pepsi has agreed to label its top-selling water more clearly, so that consumers know exactly what they're buying. Often, but not always, the repackaged tap goes through additional purification.


Washington: About the leaching involved in reusable No. 7 bottles—if you don't let the water sit in bottles in the sun, is it going to harm you? The use of plastic bottles for drinks needs to be reexamined—let's look at recycling options, bottle refund options, etc.

Laura Moser: There's still way too much we don't yet know about the leaching in #7 bottles. The subject has stirred great controversy in recent years, as polycarbonate is the main plastic used in the manufacture of baby bottles, and BPA (the chemical that polycarbonate may or may not leach) poses particular risks to young children. The industry continues to claim that #7 is completely safe, but I'm not convinced yet. I don't think that keeping your bottle out of the sun will improve its safety, but I completely agree that re-examining our dependence on disposable bottles is urgently necessary.


Silver Spring, Md.: There is a long list of good reasons to drink tap water over bottled, no question. If I lived in New York, which has water from a relatively pure, pristing source, I would drink it from the tap. Here in Washington my water comes from the Potomac. There are simply too many question marks about that source to trust it for my 23-month-old son—fish changing sex, potentially because of pharmaceutical residue, pesticide and fertilizer runoff from farms along the river, recent questions about chloramines to treat the water, etc. It is an unprotected source of drinking water. The treatment is for a limited number of contaminants, not for everything. Convince me that I should trust Potomac water.

Laura Moser: It's true, not all municipal systems are created equal, and Washingtonians face particular challenges in this respect. A study recently published by the Environmental Working Group found exceptionally high levels of contaminants in the Potomac, from all the sources that you mention. So—alas—I can't wholeheartedly recommend that you give you son unfiltered tap water, but I don't think bottled water would be much of an improvement, since it's so poorly regulated. I'd investigate purification/filtration options available in your area, since you might need something beyond the usual Brita/Pur device to clean up your tap water.


Arlington, Va.: Can the SIGG water bottle be cleaned in the dishwasher, or does it have to be cleaned by hand? Thanks.

Laura Moser: You can absolutely clean your Sigg water in the dishwasher—that's what I do—but I'd use a detergent that contains no chlorine bleach.


Laurel, Md.: My water comes from the Patuxent. Is that a significant improvement over the Potomac?

Laura Moser: I don't know anything about the Patuxent, which is probably a good sign. You can get a comprehensive list of the tap-water contaminants in your area either on the EPA website, which publishes Right-to-Know lists about community water supplies, or on the Environmental Working Group website. Unfortunately, this same information is NOT available for bottled waters—the FDA regulates bottled water under completely different (and far looser) guidelines than those the EPA applies to tap water.


Washington: To the earlier poster, keeping your water bottle out of the sun may actually help. A James Madison University scientist recently wrote an article (can't find the link) responding to a rumor that freezing your bottles can increasing leaching. He gave a more detailed explanation of the simple physics concept that heat promotes migration of molecules (i.e. the leaching chemicals) while absence of heat discourages it. Now, will it decrease that leaching rate from 100 to 99 or 100 to 10? I dunno.