Study up on the concerns of various plastic products, such as water bottles. How we handle them with heat and cold allegedly has potential to create leaching of harmful chemicals associated with the bottles composition: ‘Certain varieties of the popular, colorful Nalgene water bottles are made from Lexan, a polycarbonate plastic (usually indicated by #7 in the recycling triangle) known to leach low levels of bisphenol A (BPA), a suspected hormone disruptor (see The Bisphenol-A Debate). Because BPA leaching can increase as your bottle ages, it’s prudent to set some limits on reuse.’
http://www.thegreenguide.com/doc/114/nalgene
Below is a concise link on the number code on the bottom of the water bottles. Note the, for now, safe codes concerning codes. They all agree we should not reuse the one time use water bottles we buy in stores or in bulk at Costco.
SwittersB & Exploring 