Check this recent thread. It made me change my treatment procedure.
I have ordered the GSI coffee filter to use on a wide mouth Nalgene soft sided canteen and will put a small bag, made of noseeum netting, filled with charcoal in the coffee filter. After filling the canteen to the brim (important), I'll remove the coffee filter, use the Steripen Adventurer and finally, wash my hands and the outside of the canteen with hand sanitizer.
It's the interaction of ideas in threads like the one referenced above, that make this site amazingly good!