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What Size Hydration Bladder Should I Get?

Choosing a hydration bladder seems like a fairly straightforward process. Obviously, name brands(Camelbak, Platypus, Hydrapak) are better than generic, but they all perform the same basic job.

You might need to clean out the nasty plastic taste and make sure it’s BPA free, but you’re good to go. But there is one topic that really seems to confuse people. It’s hard to figure out what size hydration bladder you should get.

What Size Hydration Bladder Should I Get?

Before you can find a hydration bladder, you need to figure out your specific needs. How much water you need is entirely dependent on your activity. As a general rule walkers and hikers need 1 liter of water for every 2 hours on the trail(you need 1.5-3 Liters).

Runners, cyclists and climbers need to keep their pack light so typically prefer 1.5 liter water reservoirs.

Different Hydration Bladder Sizes

When figuring out your water reservoir capacity you need to first analyze your typical trip. You probably won’t need to carry a 3-liter bladder on short 1-2 hour packs.

  • Small .5 Liter Bladders: Half liter bladders are designed for short trips to the park, your local gym, and small waist packs. I actually store a few empty collapsible water bladders in my first aid kit just in case my bladder leaks.
  • 1-1.5 Liters: These bladders are great for minimalist backpackers, kids, runners, cyclists and short hikes. This is the perfect size water bladder for 2-4 hour hikes.
  • 2-2.5 Liters: By far the most popular reservoir size in the backpacking community. It’s a nice lightweight option that offers the perfect amount of water for a 4-6 hour hike. You most likely won’t have to refill your water bladder out on the trail.
  • 3+ Liters: These are made for the thirstiest hikers and designed for areas with minimal water access. When water is scarce or you don’t want to deal with purification 3 liters is perfect.

Camelbak Knows What They’re Doing

There’s a reason why Camelbak only sells hydration bladders in the 1.5-Liter, 2-Liter and 3-Liter size. These bladders are designed specifically for 1-2 hour hikes, 3-4 Hour Hikes and 6+ Hour Day Hikes. Most people never actually need a smaller/larger bladder.

Water Isn’t Light

Your water will probably be the heaviest item in your pack. Obviously, as you drink more water the weight will slowly drop. Remember that every liter of water weighs 2.2lbs, so your 3 liter water reservoir will weigh about 7lbs. So you really need to think about how much water you actually need to carry.

That’s pretty close to my average backpacking pack, sleep system and tent combined. As a general rule I like to keep my big 3 items(pack,sleep system, tent) to under 8lbs.

Go With a Maximum of 3 Liters

Throughout the years manufacturers have been making bigger and bigger water reservoirs. I’ve seen hydration bladders that go all the way up to 6+ Liters. Carrying around 6 liters of water on your back is absolutely crazy. Unless you’re traveling through the desert you’ll never need that much water.

You’re better off bringing some way to purify water out on the trail. Just bring along an inline water filter so you can quickly refill your bladder on the trail. You really can’t beat these Sawyer MINI Water Filters for the price.

Just fill up your bladder with dirty water, and it will automatically filter as you drink. The video below will show you how to add a sawyer inline filter to your hydration pack.

You Don’t Have to Fill The Reservoir

Just because you have a 3-liter water reservoir doesn’t mean you need to completely fill it. You can always go with a larger reservoir and carry only the amount of water you actually need. That’s easier said than done; I always end up completely filling my water reservoir.

For a quick (1-2 hour) hike you shouldn’t need more than 1.5-liters of water. You might need more water in hot/humid weather or while navigating difficult terrain.