Water aside, the plastic used in single use bottles can pose more of a contamination threat than the water. A safe plastic if used only once, #1 polyethylene terephthalate (PET or PETE) is the most common resin used in disposable bottles. However, as #1 bottles are reused, as they commonly are, they can leach chemicals such as DEHA, a possible human carcinogen, and benzyl butyl phthalate (BBP), a potential hormone disruptor. Also, because the plastic is porous you'll likely get a swill of harmful bacteria with each gulp if you reuse #1 plastic bottles.

Noting that the federal share of funding for water systems has declined from 78 percent in 1973 to 3 percent today, Kaplan urges consumers to "support public policies that promote safe, affordable, public tap water for future generations." Visit www.foodandwaterwatch.org and take the pledge to take back the tap, promising to choose tap water over bottled whenever possible and to support policies that promote clean public tap water for everybody. And meanwhile, invest in a safe, reusable bottle.

Better Bottles

Kleen Kanteen stainless steel water bottle w/ cap, 27 fluid ounces ($17.95; www.kleankanteen.com)

MLS Stainless Steel Thermos Bottle, 1 liter ($22.16; www.mls-group.com)

Nissan Thermos FBB500 Briefcase Bottle, 1pt ($35; www.coffee-makers-espresso-machines.com)

Sigg resin coated aluminum sport bottle, 25 ounces ($19.99; www.mysigg.com)

Platypus #5 polypropylene 2+collapsible water bottle, 2.4 liters ($9.95; www.rei.com)

Nalgene HDPE Loop-Top Bottle, 16 ounces ($4.53; www.nalgene-outdoor.com)