We just threw out all of our Nalgene and Camelback water bottles. It was a painful thing to do, but we have been watching the research and it appears that next to PVC, polycarbonate plastic (used for Nalgene) is the worst of the plastics to drink from. This research has been rejected repeatedly for several years, but there has come to be a turn around of acceptance in this dangerous material. I guess buying junk water out of Pepsi bottles is a better alternative.
Sigg bottles are great, but highly expensive. We just found a company at the natural food store that puts out a stainless steel bottle that compares to Sigg...EnviroProducts is the company and they are about 1/2 the price!