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Best Hiking Day Pack: Gregory Nano 22 H2O Hydro Pack Review

UPDATE: Before I dive into this backpack review, I want to let you know that Gregory has updated the Nano 22 hydro pack, with slight differences between the model I review below and the new model. 

The biggest differences are as follows:

  • New model:
    • 1,343 cubic in. gear capacity
    • weighs 1 lb. 3.4 oz.
    • Different hydro pack design, but still 3L
  • Old model:
    • 1,220 cubic in. gear capacity
    • weighs 1 lb. 2 oz.

The new model still offers my favorite parts about the pack, including the hipbelt, chest strap, 3+ main compartment pockets, and the same slide-in pouch/hook to hold the hydro reservoir. 

I also recommend checking out the other packs in the Nano series–they offer the same (or similar) features.

Growing up, I would take swigs of my dad’s tonic water from his hydration pack on long, exhausting hikes. The taste of the quinine mixed with the hydration pack was a sour, plastic, zinging flavor that has haunted me ever since. It ruined hydration packs for me…

So, despite being an avid hiker, I didn’t touch a hydration pack until recently, the ripe age of 30.  It was a spur-of-the-moment purchase and I bought the Gregory Nano 22 H20 hydration pack at REI (which hurt a bit at full price). But I was going on a strenuous, long hike that weekend and didn’t want to deal with heavy and cumbersome water bottles. 

So let me tell you what this Gregory Nano pack is all about and why I recommend adding it to your casual hiking gear list.

What is the Gregory Nano 22 H20 Hydration Pack?

Technically, the Gregory Nano 22 H20 is a hydration day pack with a 3-liter built-in hydro reservoir. But with chest and hip straps, multiple deep, zippered pockets and what feels like never-ending storage space, the Nano feels like a lot more than your average day pack.

The Nano 22 is part of the Nano series, which specializes in casual backpacks designed for day hikes, weekend getaways, or even outdoor concerts.


The whole Nano series is pretty similar in features and all boast the same padded mesh back panel and interior / exterior pockets. All of the Nano packs have a specialized hydro reservoir pocket (except the Nano waistline). Some come with the hydro reservoir and some don’t, so be sure to read the description carefully.

The Nano series includes:

The higher the number, the more storage capacity you have. 

Most hydration packs come in either 1, 2 or 3 liters–I opted for the 3 liter in Nano 22 because I’d rather be safe than sorry on a hike. Plus, if you’re going on a super short hike, you have the option of just partially filling the hydration pack so you don’t have to carry the extra weight.

Gregory Nano 22 Hydro Pack in Action


Whether it’s a one-hour or one-day long hike, rain or shine, snow or summer, the Nano 22 has become my go-to pack. It is so lightweight and has enough room to carry 3L hydro reservoir, my big ‘ol Nikon D3300 camera, an extra water bottle, a rain jacket, hat, snacks, headlamp and maybe sunscreen and a fleece, depending on the hike! It’s like a clown car–the pack looks small from the outside but it has never-ending storage on the inside. That is my kind of backpack.


I LOVE the waist strap–I don’t think that’s a very common feature in smaller daypacks like the Nano 22. The top-outer flap has a big zippered pocket, so I can quickly access snacks, sunscreen, a headlamp, or whatever I need easy access to. 


The Nano 22 H20 hydration pack is so comfortable that even my boyfriend wears it on our hikes! The Nano is unisex, along with all of the other packs in the Nano series. Some reviewers have reported discomfort with the straps, but I think it’s just dependent on your body build. And worst case, you can use the hip strap to take weight off your shoulders if the straps aren’t sitting right. 

Gregory Nano 22 H20 Hydration Pack Features

I love the Gregory backpack itself and its fun spark orange color, but where the pack really shines is in its hydro reservoir and how it attaches to the reservoir. After years of using my dad’s hydration packs or borrowing friends’, I’ve never used a hydro pack as well-designed for regular use as the Nano 22.  


The hydro reservoir simply attaches to the interior hook inside the pack’s reservoir pocket. There’s a wide, plastic handle on the reservoir so you can get a good grip on it while filling it under a faucet. 

The drinking hose on the reservoir clips in so you can remove it if needed. The mouthpiece has a lock-stop so you can close the valve to prevent spillage. But my favorite feature is probably the adjustable hook so you can hang it off of something in order to dry properly. This is lightyears ahead of what my dad’s hydro packs were like!


I also like that the backpack is designed like a stuff sack, with an easy-pull drawcord to quickly cinch up the top. The top zippered pocket securely covers up any opening from top of the stuff sack, so I know my items are secure even though they aren’t “zippered” in. 


The die-cut backpanel helps cut down on overheating thanks to its mesh, breathable material (that’s also impressively cushy and comfortable). The straps also have loops to hook your reservoir hose into, so it isn’t just flopping around while you’re walking or hiking around.  

Gregory Nano 22 H2O Hydration Pack spark orange

The design makes use of every little space on this pack–from the deep interior side pocket, the stretchy exterior mesh pocket, the bungee straps across the front of the pack (great for holding a light tripod or windbreaker), and even the zippers have reflective attachment loops for connecting things like water bottles or flashlights. 


Summing It Up

Gregory’s Nano 22 H20 hydration pack is my go-to pack for nearly any outdoor activity. It has so much space for holding all of the essentials (and then some), while maintaining a light, comfortable and airy feel. The hydro reservoir is really easy to remove and insert, is easy to clean and doesn’t give my water a funky taste. The hip strap and chest strap make all the difference for balancing your load. It really is like a backpacking pack, but in “nano” form.

I recommend checking out the Nano 18 or Nano 20 hydro packs if you want something slightly smaller and more compact, but with similar features. 

And if you’re on the hunt for some top-notch casual hiking wear to match this amazing day pack, check out my review of KUHL’s Freeflex Dash jogger pants or KUHL’s The One Shell jacket!

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