If you need a place to get a Fresnel lense magnifier online, REI has them.

On water purification I exclusively use the Katadyn's Micropur MP1 (or boiling of course) for my water purification needs when hiking and for my car kits as well as my EDC. About every other weekend I go on a long hike in extremely hot weather (this time of year) where carrying the amount of water I need is simply not possible. I have had great success with the Katadyn's Micropur MP1 tabs. I have had to use them on some very questionable water and have yet to get sick (knocking on wood). What I do in when hiking to avoid the long wait time associated with the Katadyn's Micropur MP1 tabs is use them in conjunction with an (chemical-free) activated charcol filter water bottle. The filter immediatly removes the bacteria-based nasties and then the Katadyn's Micropur MP1 tabs are left only with the job of killing the viruses, which they do rather quickly. The way I understand it they only take about 15 min to kill viruses. I give it 30 min just to be safe <img src="/images/graemlins/laugh.gif" alt="" />. I keep one of these bottle filters in my car kit as well. For EDC I only carry the tabs (6 of them). Another side note on the Katadyn's Micropur MP1 tabs... I have had success cutting them in half right through the foil packaging (requires a razor sharp blade) with out having them come in contact with my skin. This is handy when I only have smaller containers to work with. I know you can use the tabs with less than a liter of water but I can't see any reason to injest more chemicals than is necessary in any situation. <img src="/images/graemlins/smile.gif" alt="" />