The Best Hydration Packs for Day Hikers

Some companies say their women's bags accommodate wider hips, but we didn't note any marked differences in that regard between the men's and women's packs we tested, even during our longer hikes. In some cases, the only difference beyond color was that the men's packs were a few inches taller than the women's packs. Thus, people 5-foot-8 and under will likely be most comfortable wearing so-called women's packs. People over 5-foot-8 will probably prefer men's packs. A good hydration pack will have the following qualities: Comfortable to wear: The best packs have hip belts, which place the bulk of your pack's weight on your hips, relieving your shoulders and leading to more stability during rocky, root-filled hikes. In recent years, lower-priced popular packs, such as the Osprey Skarab and Skimmer, have replaced their hip belts with unpadded waist straps; it's not a dealbreaker, but it isn't ideal if you're hiking for longer than a few hours. We also looked for packs with padded shoulder straps and articulated backing, usually made with some kind of mesh; this keeps the pack away from your back and prevents excess sweat from building up throughout the hike. Space for a reservoir: In recent years, hydration systems have become so popular that even backpack makers that don't provide reservoirs with their packs include sleeves and slots so that a bladder can be added later. The correct size for a day hike: Ideally, you should have 4 to 8 ounces of water per hour of hiking. By this metric, you'd want to pack at least 1 liter of water for a four-hour, moderate-intensity half-day hike and 2 liters for a full-day hike. We looked for bladders that held at least 1.5 liters of water, and we kept our search to bags that had between 16 to 28 liters in storage capacity. That's large enough to fit all the things we needed on our day hikes: snacks, a first aid kit, an extra jacket, an emergency blanket, a headlamp, and incidentals. A reservoir that's easy to clean and fill: Different reservoirs have different clips and zipper systems on the top, which make them easier (or harder) to fill. We opted for those that were well reviewed as easy to fill and non-leaky. Some hoses also detach from the bladder themselves, which makes cleaning the systems easier. Some companies offer replacement hydration systems, too, which is important -- the plastic on the reservoirs can break down over time, often before the packs wear out. A hydration system that's easy to use: Most bladders come with a hose that attaches to the pack's straps; we looked for systems that were simple to set up (no complicated configurations of snaps and ties, please!) and mouthpieces that were rated by online reviewers as comfortable to use. All of the hydration systems we recommend in this review are BPA free. In addition to traditional hydration packs, we looked into other types of hydration systems. Trey tested water bottle adapters that add a drinking hose to hard-sided bottles (like from Nalgene and Hydro Flask), which allow for easier drinking while bottles are stored in pack pockets. He also tested insulated hydration bladders intended to keep water cold in hot weather or to keep water from freezing in cold weather. For testing, we started by filling up the reservoirs in the sink (not always an easy task). Then we did an initial taste test, noting any plasticky flavors in the water. Next, we took each pack out for a 3- to 5-mile hike. For these hikes, we packed each bag to its full water and gear capacity. A pack's weaknesses -- those nagging pressure points, or a lack of balance -- reveal themselves more quickly when you're carrying a full load. While out on the trail, we also took notes on comfort, moisture-wicking, ease of access to water and gear, any leaks, and overall bag experience. Then we put the hydration bladders through additional paces at home: We filled them up, compressed them under 20-pound bins for five hours (to simulate being thrown in the trunk under lots of other packs), and then checked for leaks. The bladders went into the freezer overnight so we could see how they might handle being accidentally left in the car overnight in winter. We checked for damage again. For the insulated bladders, we also measured how long they stayed frozen under direct sunlight. After this, we left the packs out to dry for 12 hours, checked for retained moisture (so much) and made notes about how easy the bladders were to clean (not easy). Finally, we took our favorites out on the trail for a final spin. And we scoured online reviews for notes about durability over time and looked back at our own long-term testing data.