MSR Thru-Link InLine Microfilter

While many filters have the option to work in-line with a bladder, the hollow-fiber Thru-Link is designed specifically for that purpose, and attaches to any reservoir with plastic adapters—no hose-cutting necessary. The .2-micron filter weeds out bacteria and protozoa (though not viruses) and is rated for up to 1,000 liters. Testers enjoyed a flow rate of just over 1 liter per minute even after multiple uses. “On our trip in the canyons of Zion National Park and Kanab, Utah, I filtered water that was often sandy and silty and the filter never clogged, though the flow rate did slow slightly,” one tester says. The Thru-Link fits in the palm of your hand, impressive given that it contains a carbon component for filtering out bad tastes and heavy metals (which is good for the lifespan of the filter). Bonus: It works in a gravity setup, too. $40; 2.5 oz.