Chaosmagnet, I appreciate the consideration you have given to my and other suggestions and I respect your choices . I usually don't argue after the decision is given, but you did end in part with an inquiry about what bottle purifiers can deal with chemical and biological contamination. The answer is : Seychelles Advanced (both bottle and straw), Katadyn Extream XR, Berkey and Sawyer, albeit the last two might also require tablets or bleach. I personally chose both the Seychelles Advanced bottles and straws, as they are the lightest and smallest. In other apps, I've used Katadyn too. Finally, the MyXcaper is fairly small and very light and the five year model is the better value. But, if you need the mask, you'll also need goggles for your eyes. Xcaper has them as a kit, but swim goggles seal better, can be bought with anti fog coating and are cheaper.