I like to rely on multiple means of clean water (SteriPen, gravity filter, iodine in a pinch), because we go through a lot of it. But nothing makes it as simple as the UV-purifying All Clear: Fill the .75L bottle with river water (an optional $15 pre-filter is available to remove chunks), screw on the top, press button, and in 60 seconds the LCD readout tells you it’s safe to drink. From there, refill everyone else’s bottles and keep going—for up to 16 gallons on a single charge. And to keep it running for days, bring along a portable power pack like this one from Trident, which should recharge it five times. $99.