+1 with comms comment, I'll stick with my Steripen as well with 30 tab micropur tablets as backup. You just have to make sure the water is relatively clear, I haven't got sick with one yet and I carry a katadyn Combi for a prefilter for really really bad dirty water in case, but I rarely need it for where I go, the steripen is usually all I need. The steripen is awesome for me with the capability of running it 100% with no batteries off of solar cells in a emergency. UV filtering has been around for quite awhile, used for purifying water as well as air and instruments, it's a proven technology with it's disadvantages are murky water, relying on electronics and the lamp will need changed years down the road. I wonder if the micropur tablets in time may have to be replaced if not used in a long time (like a shelf life), I'm not sure though, I know Iodine lasted for years but doesn't kill the good stuff. Anyway you wont have the 4 hour dwell time with the steripen and that can mean life or death in some cases, both have their advantages and disadvantages, that's why I carry both.