Have you used other filtration systems currently available? As far as I know all use either some pumping mechanism or gravity pressure, or in the case of the Sawyer squeeze system the pressure of squeezing the vessel which forces the water through the filter.

What about a bladder with a built in UV sterilizer in the bladder and a light charcoal filter on the outlet tube. The UV light would kill the bad stuff and the filter would improve the "quality" of the water without greatly restricting flow.

Hey better hurry up and patent that idea before it's in the public domain..oops too late.