Staying hydrated in the mountains is incredibly important for performing at your best. So, you need a system that enables you to hydrate on the go and encourages you to drink throughout the day.
For me, that system is a hydration bladder. While water bottles might work for some mountaineers, I’ve found that I drink far more water when it’s accessible from a hose hanging over the shoulder strap of my pack. Hydration bladders are easy to refill in the field, plenty durable for alpine climbs, and never leak.
In this guide, I’ll review the 5 best hydration bladders for hiking and mountaineering. I’ll also explain how to pick the right hydration system for you and how to keep your bladder clean between trips.
My Review Process
To me, the best hydration bladder is the bladder that holds and delivers water trip after trip without fail. I tested out some of the top hydration bladders on the market on climbs in the North Cascades to see which ones are easiest to drink from and which ones can stand up to repeated use.
The Platypus Big Zip EVO is the hydration bladder I use for most trips into the mountains. It’s well-designed and just does its job without much fuss. I’ve never had a leak after years of using this durable hydration bladder and it comes with a lifetime guarantee.
The thing I like best about the Big Zip EVO is how easy it is to refill. Platypus added a piece of flexible plastic that you can pinch to keep the mouth of the reservoir open while holding it in the air. Then the bag closes with a simple zipper and slide.
Another nice touch is the detachable hose. It makes cleaning the hydration bladder much simpler, and ensures that you only have to replace the hose—not the whole bladder—if you spring a leak. The hose is capped with a simple bite valve that offers a fast flow rate. There’s a simple lock mechanism on the valve to prevent leaks, too.
The Platypus Big Zip EVO is available in 1.5, 2, and 3-liter sizes. The plastic is BPA-free and phthalate-free.
The Gregory 3D Hydro is another well-designed hydration bladder with a lot of features to recommend it.
Instead of a zipper, this bladder uses a screw-top lid that’s simple to secure. The lid is attached to the bag, so you can’t accidentally drop it in a creek. The bladder also has an integrated handle on the front of the bag, making it incredibly easy to hold the reservoir open when refilling it. The hose is detachable both at the reservoir and at the point where it enters your backpack, making it easier to remove the bladder from your pack without unthreading the hose. It also has a clip to keep it in place on your shoulder strap.
The suction valve on this bladder is perhaps its most unique aspect. Instead of a bite valve, the Gregory Hydro uses a push-button valve. It’s less likely to leak when you’re not drinking from it, but it also requires you to use a hand to push the button when you want water. It’s not my favorite design, but it’s easy to get used to. It’s also cheap and easy to replace the valve.
The Hydrapak Shape-shift bladder is one of the lightest hydration bladders on the market, weighing in at a scant 4.9 ounces for the 2-liter model. Granted, the difference between “ultralight” and regular bladders is only an ounce or two. But if you’re trying to shave weight off your mountaineering, hiking, or trail running kit, those ounces might matter.
The Hydrapak Shape-shift reservoir saves weight largely by leaving out features that make it easier to refill. You’re on your own to figure out how to keep the top of the bag open when pouring in water. The zip-top closure is just as robust as the similar closure system on the Platypus Big Zip EVO, and it didn’t leak throughout my testing.
One thing I loved about the Shape-shift’s design is that the reservoir itself is fully reversible. That is, you can turn it inside-out for cleaning. The hose is also detachable and features an auto-shutoff valve to prevent leaks.
The CamelBak Crux reservoir is one of the best hydration bladders for narrow packs. It’s the perfect size for mountain running vests, but it also works well if you have a narrow mountaineering backpack. The shape of the reservoir is tapered towards the bottom, and that makes a huge difference when you’re tight on space.
Beyond that simple design tweak, the Crux has everything I look for in a hydration bladder. It offers a quick release hose system with a bite valve and locking mechanism, an integrated handle to make refilling easier, and durable construction. It’s also BPA-free and features Hydroguard bacteria growth inhibitor technology.
The only drawback I found to this bladder is that it can be hard to clean. The bag can’t be flipped inside-out, and the screw-top lid is too small to allow your hand inside the reservoir for scrubbing.
The MSR DromLite is one of the most unique hydration bladders on the market right now. In essence, it’s an affordable, ultralight reservoir that’s primarily designed for carrying extra water. It doesn’t come with a hose, but MSR sells one that fits the 3-in-1 cap. Alternatively, you can drink from a nozzle built right into the screw-top lid.
The beauty of the DromLite is that the 2-liter version weighs just 4.6 ounces. It’s lighter than most water bottles, compresses to a tiny size when empty, and can be used as either a standalone reservoir or a hydration bladder. It’s particularly good for mid-summer climbs when water is hard to find above treeline.
Of course, this style of bladder won’t be for everyone. If you’re primarily looking for a way to drink on the move, I’d recommend sticking with one of the purpose-built hydration bladders I recommended above.
How To Choose A Hydration Bladder For Mountaineering
When picking a hydration bladder, there are a few important things to consider.
The most important decision you’ll need to make when buying a hydration system is how much water capacity you need. Most of the hydration bladders I reviewed come in 1.5, 2, and 3 liter options.
Personally, I use a 2-liter bladder, plus carry a 1-liter water bottle for a day trip. I like having the water bottle because it’s hard to know how much water is left in my bladder when I’m moving, but I always know exactly how much water is reserved in the bottle. However, it makes just as much sense to buy a 3-liter bladder and carry all of your water in there.
If you’re not sure what bladder size to pick, err on the side of buying a bigger bladder. You can always fill it halfway if you don’t need 2 or 3 liters of water, like in cold weather.
Size and Weight
Another thing to consider when picking out a bladder is whether it will actually fit in your backpack when the water reservoir is full. Most mountaineering and hiking backpacks are hydration bladder compatible and can fit most bladders. But if you climb with a trail running pack or a narrow backpack, you might need a bladder with a slim profile like the CamelBak Crux.
As with all mountaineering gear, weight is a consideration when choosing a bladder. That said, the lightest bladder I reviewed, the MSR DromLite, weighs 4.6 ounces. Meanwhile, my top pick, the Platypus Big Zip EVO, weighs 6.0 ounces. So, don’t get too hung up trying to shave ounces in your hydration system.
All of the bladders I reviewed are BPA-free, and the Platypus Big Zip EVO is also phthalate-free. Choosing a BPA-free reservoir is especially important if you plan to fill the bag with hot water, since heat can cause chemicals in the plastic to leach into your water and leave an unpleasant taste.
While manufacturers use slightly different plastic blends, what ultimately matters is how durable the reservoirs are. All of the bladders I tested held up during extensive testing, and my Platypus Big Zip EVO has been in my pack for years.
Hose and Valve
One thing that’s a must-have item for me in a hydration pack is a detachable hose. Being able to detach the hose makes it easier to refill your bladder without the drinking valve falling in the dirt. A quick connect mechanism also makes it easier to clean your bladder after you get home. Plus, detachable tubes are replaceable—so if something happens to your hose but your reservoir is fine, you don’t need to buy a whole new hydration bladder.
It’s also worth looking at the valve. I personally prefer fast flow bite valves, but there are also push-button and pressurized bladder systems. These are interchangeable across most brands, so you can swap out your valve if you’re not happy with the one that comes included with your bladder.
Most hydration bladders use one of two types of closing mechanisms: a zip-top or a screw-on lid. Neither is necessarily better than the other, but there are some general differences. A screw-on lid usually makes it easier to refill your bladder, especially if there’s an integrated handle. However, a zip-top bladder offers ease of cleaning since you can turn the entire bag inside-out.
Cleaning Your Hydration Bladder
Unfortunately, hydration bladders can get pretty gross over time. Even if you only ever put water in your bladder, mold can grow in the water reservoir and hose if you don’t clean your hydration system. If you put sugary drink mixes in your bladder, mold can start growing as soon as you get home from the mountains.
Trust me—it’s much easier to clean out your bladder before it gets moldy. Once you’ve got mold, getting it out requires a lot of scrubbing, often in spots that are hard to reach. So, it’s a good idea to clean your bladder after every trip.
Rinse out the reservoir, hose, and valve with warm, soapy water. Then leave your bladder to dry. It’s hard to get all the moisture out, so I also like to store my bladder in the freezer after cleaning it to prevent the growth of bacteria.
Hydration bladders make it easier to stay hydrated throughout the day by allowing you to drink on the go. They’re my preferred way to carry water in the mountains, even if I often take a water bottle along as well. I recommend the Platypus Big Zip EVO as the best hydration bladder for mountaineering thanks to its seamless design and durability. The Gregory 3D Hydro bladder is a great alternative if you prefer a screw-top closure to a zip-top closure.
A hydration bladder is simply a plastic reservoir with a hose attached to it. You can run the hose from the bladder to the shoulder strap of your backpack so it’s easily accessible.
You can fill a hydration bladder using the zip-top or screw-lid opening. Always make sure you’re filtering water in the mountains before adding it to your bladder.
Taking in electrolytes in the mountains is critical to balancing your hydration. You can fill a hydration bladder with Gatorade or energy drinks. Just be sure to clean your bladder thoroughly afterwards.
Clean your hydration bladder after every trip, or else it can grow mold. Use warm soapy water, thoroughly dry your bladder, and then store it in the freezer.
A hydration bladder makes it easy to drink on the go. You’ll be more likely to drink throughout the day when you don’t have to stop and pull out a water bottle.
Most hydration bladder manufacturers sell their products online. You can buy any of the top bladders I recommended from REI’s website or directly through the manufacturer’s website.
*The information on this site is based on research and first-hand experience but should not be treated as medical advice. Before beginning any new activity, we recommend consulting with a physician, nutritionist or other relevant professional healthcare provider.