Filter purifications systems are passe.

I've used a Steripen for several years now. I think it is the best water purification system. No filters to buy. No filters that can go bad. No iodine pills that affect the taste.

Steripen kills viruses as well as Giardia and bacteria. I carry my Steripen in my Nalgene bottle with an extra set of batteries. I take it on trips to Mexico or anywhere the water is suspect. You can use it in a restaurant to purify the glass of water they bring.

I've never gotten sick since buying by Steripen.

http://www.steripen.com/