Find Your Store
Home Page
When autocomplete results are available use up and down arrows to review and enter to select. Touch device users, explore by touch or with swipe gestures.
Expert Help

Cart, contains 0 items

Home Page

Cart, contains 0 items

When autocomplete results are available use up and down arrows to review and enter to select. Touch device users, explore by touch or with swipe gestures.

Gregory
Inertia 18L H2O Hydration Pack

4.857142857142857 out of 5 stars
7 Reviews
Current price: $82.46 Original price: $109.95
25% off
Color:Redrock

Size:

Size Chart

Quantity

Only 4 In stock


Why We Like the Inertia 18L H2O Hydration Pack

For day hikes where one water bottle won't cut it, we load up the Inertia 18L H2O Hydration Pack to stay equipped for a long day on the trail. The included reservoir stays secure in its dedicated zipper pocket, and the inline hose conveniently detaches for easy refills that don't require us to remove the hose from its shoulder harness.


Details

  • Hydration pack holds the essentials for long day hikes
  • Sturdy nylon is lightweight and resists trail wear
  • DWR treatment sheds light rain to protect contents
  • Includes 2L quick-drying reservoir for ample hydration
  • 3D multi-density foam backpanel for a comfortable carry
  • Removable hipbelt offers more support if needed
  • External zipper pockets keep the essentials at hand
  • Item #GREZ084
Responsible Collection
Bluesign Approved, Recycled/Repurposed
Material
[face fabric] 210D HD nylon, 420D HD nylon, PFC-free DWR coating, [lining] 135D polyester, PFC-free DWR coating
Volume
18L (1098cu in)
Support/Suspension
3D foam back panel
Shoulder Straps
multi-density foam
Waist Belt
detachable
Hydration Compatible
yes
Reservoir Included
2L 3D Hydro Reservoir
Access
front panel
Pockets
1 zippered top, 1 zippered side, 2 side mesh
Trekking Pole Carry
yes
Weight Capacity
20lb
Dimensions
[packed] 19.3 x 9.8 x 7.5in
Claimed Weight
1lb 3.5oz
Activity
hiking
Manufacturer Warranty
limited lifetime

What do you think about this product?

Overall Rating

5 based on 7 ratings

Review Summary

1 Stars - 0 reviews
2 Stars - 0 reviews
3 Stars - 0 reviews
4 Stars - 1 reviews
5 Stars - 6 reviews

Customer Images

View

Selecting an option will reload the available reviews on the page
5 out of 5 stars

August 4, 2025

Outperformed My Expectations!

30 miles down with this thing on my back. I was in and out of Yellowstone and the Tetons this last week and did put over 30 trail miles on this bag. I am very impressed with how it performed. It was lightweight, comfortable and super easy to use. The hydration pack was perfect and very intuitive to use while filling up or on the trail - the magnet attachment to the chest strap is just a gem. I also love how the chest strap has a magnetized closure which makes it easy to use, again, and quite secure. The main pocket was the perfect size for me, I was able to fit a rain jacket, lightweight fleece, snacks, bug repellent, sun protection, snacks and a few other goodies with room to spare. It helped me to feel prepared for whatever might come my way, and when the rain came I was prepared! The pockets are easy to open and the small ones can store all my little goodies, which I love. The shoulder straps were supportive and very lightweight which helped it to be comfortable to wear for hours on end, I never really wanted to take it off! This comes with a thin waist strap that I don’t feel like was super helpful on this size of bag, buckling it in definitely helped put some of the little bit of weight I was carrying on my hips but I didn’t think it was very necessary. If the straps were thicker or more substantial, I might like them better. But I do like that they are removable. Maybe that could be combined? This was the perfect size for my needs and doing several daily hikes. It is good to just grab and take with you on any adventure you’re eyeing. Thanks Gregory for such a well made bag!

user image
TuckerW
Gregory

Originally reviewed on Gregory

5 out of 5 stars

September 24, 2024

Intertia 18L for the Win!

I purchased this daypack for 7 days of hiking in Yosemite. Inside the pack, I carried a full water bladder, 1 fleece hoody, 1 rain jacket, 1 wind shirt, 1st aid kit, snacks and a small pair of binoculars. On the outside, I attached my hiking poles and a full 1 L Nalgene bottle. I am 5'11 and weigh 180 lbs. The pack fit me really well once I dialed it into how I like to wear a daypack. I removed the hip belt because it wasn't a feature that I wanted to use. The pack carried my loadout of 15 lbs nicely. The shoulder straps are minimalist-style but are still comfortable. I only experienced shoulder fatigue after 8 or 9 hours of use on my longer days on trail. Overall, I am really pleased with this pack. I tried on several daypacks before I made the purchase and I feel like I got exactly what I was looking for.

McClelland333
Gregory

Originally reviewed on Gregory

5 out of 5 stars

January 22, 2024

Perfect day trip pack

I love this pack for day trips, both hiking and snowshoe. The bladder is easy to access, fill, and secure. The main compartment has sufficient space for a first aid kit, food, wind/water proof shell with room to spare. I only wish that it had a better means to secure snow shoes for hikes where they are not initially needed.

user image
Neil S
ExpertVoice.com

Originally reviewed on ExpertVoice.com

5 out of 5 stars

August 22, 2023

Awesome Day Pack

This is a fantastic and comfortable day pack. I have used it on a few hikes and it has been awesome. The mesh panel helps with breathability, but if you run hot you’ll still sweat with this pack. I love the separate hydration sleeve and the clip that keeps the hydration pack steady. The hydration pack it comes with is amazing and easy to clean. The only think that could make it better would be a rain cover to go with the pack.

Aaron W
ExpertVoice.com

Originally reviewed on ExpertVoice.com

4 out of 5 stars

May 14, 2023

Would love it, if…

I like the fact that this pack has three outer mesh pockets, one 3L water reservoir compartment including hose routing straps, and a comfy breathable meshed back support plus shoulder straps. I WOULD LOVE this pack if it had one additional inner pocket for keeping valuable electronics and wallet away from easy reach and thieves. I WOULD ALSO LOVE this pack if it had a single-handed, quick-pull draw cord with a weather flap seal in order to access the MAIN COMPARTMENT without the use of a cumbersome zipper, which slows me down when in outdoor conditions. Other than that, this pack is beautifully made.

Angelicious
Gregory

Originally reviewed on Gregory

5 out of 5 stars

April 3, 2023

Outstanding Quality

This H2O backpack is awesome in every aspect. Quality materials, great fit and many options.

Mark S
ExpertVoice.com

Originally reviewed on ExpertVoice.com

5 out of 5 stars

May 27, 2022

Absolutely Perfect Bag for Day Hikes + Hydration

[This review was collected as part of a promotion.] I did receive this pack as a #giftedproduct, but that in no way influences my review or remarks. I have been a huge fan of Gregory for years. I use their bags for backpacking, day hikes, and commuting. Their bags are top-notch quality, feature-rich and comfortable. The Inertia 18 is no exception. Why do I love it? The small footprint gives way to a massive amount of capacity without feeling too bulgy. The bag itself has a shape that it doesn't lose when empty - making it easy to pack up, sort through, and clean up. It's got all the bells and whistles that can be jammed into a small package: Amply sized main storage compartment, a separate hydration pocket, a front knickknack pocket at the top, a mesh water bottle side pocket, and a bonus zip pocket on the other side. The back panel mesh on the back allows pretty good airflow, and the straps are nice and lightweight so they don't feel too bulky or heavy - even when the sweat hits. But the gem: The hydration system. Gregory absolutely killed the game with their hydration systems - hands-down best on the market. This bag comes with a 2L bladder which is the perfect size for most hikes that I do. On hot days, I will throw an iced-down water bottle in the side pocket. (I Live in AZ). The bladder has a quick release system meaning you can completely pull it out to fill it up. So easy and clean. It has a wide mouth to make filling simple. There is a handle to help carry the bladder outside of the bag. The lid twists on and off with ease and is very secure - which is where many other brands go amiss. The INertia's hydration compartment has a built-in hook to hang the bag from so it doesn't slump around, and because of the hardened back panel of the bladder, it stays in place - and keeps that water upright and ready to flow. It's also the simplest water hydration system to clean. Gregory integrated a hook for you to be able to hang the bladder upside down. I usually throw a paper towel or small towel in the bottom to soak up any water, making sure to keep the mouth open for airflow while the bladder dries itself out.

user image
TheAdventureDispatch
Gregory

Originally reviewed on Gregory

Related Categories

Top Hydration Packs Product Photo

Hydration Packs

Related Searches

Gregory Inertia 18L H2O Hydration Pack reviewBest hydration pack for day hikesLightweight nylon hydration pack for outdoor adventuresDurable DWR treatment hydration pack for wet conditionsComfortable multi-density foam back panel hydration pack2L reservoir included in Gregory Inertia hydration packHydration pack with trekking pole carry featureVersatile hydration pack for men and womenEco-friendly hydration pack with recycled materialsCompact 18L hydration pack for long trailsHydration pack with removable hipbelt for added supportGregory Inertia hydration pack specifications and features

Learn more about Inertia 18L H2O Hydration Pack