Hydrapak Seeker 3L Soft Water Bottle Review

The Hydrapak Seeker 3L soft bottle has a 42mm opening and graduated measurements printed along the side.

The Hydrapak Seeker 3L is a 100 ounce (3 liter) soft water bottle that weighs 3.1 ounces empty and has a 42 mm opening. The big benefit of using a soft bottle for backpacking is that it can be rolled up and tucked out of the way when it’s not needed.  However, the Seeker 3L is colored brown instead of being transparent, making it difficult to see if the water in the bottle is clear or turbid. While this doesn’t matter if you fill it with safe tap water, it’s not ideal for backcountry use where water clarity has a big impact on water treatment speed and effectiveness.

Hydrapak Seeker 3L Soft Water Bottle

Easy to Clean
Hydration System Compatibility
Water Filter Compatiility

Compatible with Katadyn BeFree

The brown color and lack of interoperability between the Seeker and popular backpacking water filters makes it less than optimal for backpacking use.

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Detailed Description

The Hydrapak 3L Seeker is a brown colored soft bottle with a flat bottom. It is made with thermoplastic urethane (TPU) which is BPA-free and PVC-free. It has a printed scale on the exterior that measures approximate volume in units of 20 ml up to 3000 ml. The volumes are “approximate” because being soft, the sides of the water bottle are easily deformed to alter the amount of water it actually contains.

Despite having a flat bottom, the 3L Seeker will not stand up by itself, either when it’s completely or partially filled with water. The material it’s made with is so flexible that the sides of the bottle buckle under its own weight and it topples over.

The bottle has three external webbing loops so you can attach it to the outside of your pack, although I wouldn’t recommend that if you hike off-trail because the bottle’s TPU construction won’t stand up to abuse by aggressive vegetation. However, the webbing loops do make it possible to hang the bottle in a gravity-filter configuration, when used with a compatible water filter like the Katadyn BeFree Filter.

The Hydrapak 3L Seeker Soft Bottle has 3 welded webbing loops on the outside of the bottle
The Hydrapak 3L Seeker Soft Bottle has 3 welded webbing loops on the outside of the bottle.

The Hydrapak Seeker 3L soft bottle can be safely frozen but is not designed for use with water warmer than 140 degrees. Doing so risks having the welded construction fall apart as noted by Hydrapak customer service when I inquired.  How can you tell how hot water is in the field, when you’re on a backpacking or camping trip, without a thermometer? Good question. Hot tap water is about 120 degrees, while the temperature of hot water in your dishwater is about 150 degrees. Boiling water is 212 degrees. My advice, keep this bottle out of your dishwasher and avoid using it to store any hot water. I’d also recommend keeping it out of hot automobiles in the sun when unattended.

Water Filter and Treatment Compatibility

The Katadyn BeFree is the only water filter compatible with the Hydrapak 3L Seeker or 2L seeker which have 42 mm openings. This is a non-standard size and much larger than those found on most other soft bottles or everyday soda water bottles, which have a 28 mm opening.

While you’d think that the larger 42 mm opening in the 3L seeker bottle would make it easier to fill, I haven’t found that to be the case in standing water without a current, like you find in ponds or lakes. The soft walls of the bottle collapse when you push the bottle underwater or grip it in your hand and displace the space that would otherwise be filled with water. This is less of an issue with the harder sided soft bottles made by Platypus or Evernew, which do not collapse, even though they have smaller openings.

The Hydrapak 3L and 2L Seeker bottles are only compatible with the Katadyn BeFree Water Filter.
The Hydrapak 3L and 2L Seeker bottles are only compatible with the Katadyn BeFree Water Filter.

If you use Aquamira water purification drops or other purification tablets the brown color of the 3L Seeker prevents you from being able to determine the turbidity or degree of suspended solids in the water you want to purify. This can have a big impact on the required treatment time, extending it from 15 minutes for clear water to 4 hours or more for turbid or cloudy water. You’d be much better off using a transparent soft bottle like the Platypus 2L bottle, if you use a chemical water purification method.


I’m very hesitant to recommend the Hydrapak 3L Seeker soft bottle for backcountry use. Its brown color makes it impossible to see if the water in it is clear or not. The seams of the Seeker bottles risk coming undone if it is exposed to water or air temperatures above 140 degrees and the non-standard sized opening makes it incompatible with most water filters including the Sawyer Squeeze or Sawyer Mini.

If you’re thinking about a Seeker soft bottle as part of a gravity or squeeze setup with the Katadyn BeFree Water Filter, I’d encourage you to bring a backup water treatment system and container, in case your Seeker Bottle is damaged, since the BeFree is incompatible with any other manufacturer’s bottles. Your backup could be as simple as Aquamira drops and a cook pot or a soda bottle. But until Seeker soft bottles are as ubiquitous as conventional soft drink bottles or Platypus soft bottles, I encourage you to hedge your bets if you’re backpacking alone or someplace without easy access to a replacement Seeker bottle. Call me cautious. I’ve had soft bottles and water filters fail on me on trips in the middle of nowhere, and having a backup system has saved my ass.

Disclosure: Hydrapak provided the author with a product sample for this review.

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  1. I use a Nalgene 96 oz flexible canteen. It is clear, stands upright, and roles up for storage. I have an adapter lid for my Sawyer. Supper handy and cheap.

  2. I agree with your concerns about this water bottle. The only use that I see for it is when I’m on large group outings (like my Boy Scout troop backpacks) that call for a pump instead of a personal water treatment solution so only potable water goes in and/or when camp isn’t set up near a water source, requiring someone to water sherpa.

    Even then, I believe this is heavier than the Nalgene 96 oz canteen, lacks the semi-rigidity of the Nalgene for filling the bottle, and doesn’t fit the adapter for a Nalgene. The only real advantage is that its size is minuscule when folded up (enough so that it fits in the same bag as my water filter). Shawn lists some further advantages of the Nalgene above as well.

  3. Thanks for the review. This bottle looks like kind of a non-starter.

  4. I know people have complaints about the Nalgene flexible canteens, but I’ve yet to find anything better for the compromise between weight, ease of filling, and durability.

  5. I use a Seeker 3L with my BeFree filter in a gravity system, and have had zero issues with the Seeker. Granted, I am hiking in areas where water turbidity is not usually an issue (Sierras, Wind River Range). The Seeker has held up perfectly in my use case. It is stored in my pack in its stuff sack until we arrive at our evening campsite, then rigged from a handy tree branch by its built-in webbing loops.

    My backup system, which I use during the day while hiking, is the Katadyn 0.6L soft bottle that comes with the BeFree filter and a Platypus 1L soft bottle for additional carrying capacity. I always have a few Aquamira tabs in the first-aid kit as well.

    So far at least, the Seeker has proved to be durable piece of kit, and I love that it packs very small. A 42mm – 28mm adapter cap would be a great addition (are you listening, HydraPak?). In 40 years of hiking the mountains of the west, I have yet to collect water at or above 140 degrees, so I don’t know that I am too worried about seam failure from hot water.

    • Jay, this is exactly the setup I plan to use on the JMT this summer. I am glad to hear that someone else has had good results with it. I grew increasingly frustrated with my Sawyer Mini last season (my first season doing multi-day trips). The slow flow rate and increased need to backflush was kind of a bummer. I picked up the BeFree on sale at REI last fall and I’m super excited about it. With twice the flow rate and no need need to carry a separate syringe for backflushing, I think it’s going to be a much more efficient hydration system for me.

  6. Thanks for this! I was just looking at this and on the fence, and your review brought out some things I hadn’t considered. Much appreciated!

  7. It’s a fine system for backpacking but really shines for bike packing where the shape and flexibility allows it to fit into a top tube bag better than most other products I’ve tried. There are adapters for the opening size and I currently use it with a hose and bite valve. With the Katadyn filter, I can add the hose, fill and go. No issues with quality stuffing it into a crowded bag and I’ve found the material very forgiving. Backpacking uses have been fewer but I’ve not experienced the filling difficulty (technique?) nor has the color been an issue (I too live in a region where clear water access isn’t an issue). Ultimately, I really like the soft sided water treatment options. With this system or the Sawyer (the other style I use), I’m very happy to be able to ditch the old pump style filters.

    • This Friday I review the Platypus Meta Bottle 1L + Microfilter which I think is an even better system if you use a water bottle cage. It uses an almost identical filter but the bottle is a little bit more rigid and it can still be used in squeeze mode for bulk water filtration.

  8. Got to test this bag a week ago for several days as part of my filtration kit on a backpacking trip, as well as water container car camping. Wished it was clear, but still loved it. Really liked the wider opening versus the old platys. After a week I cannot speak for its durability, but I am confident at the moment and happy with it. Worked very well with the BeFree filter

  9. Dana P. Winternheimer

    I recently picked up a two pack of the Hydrapak Seeker 2L on Massdrop as a lighter alternative to my old MSR Dromedary bags. After reading the Katahdyn Be Free review here, I added one of these to my kit to replace my trusty First Need filter. I haven’t had a chance to try out the new filtration set up yet, but am looking forward to it. There have been some concerns expressed over the durability of the Hydrapak Seeker but my experience with another Hydrapak product would indicate that these concerns are unfounded. I have had a Hydrapak Stash 750ml collapsible bottle for almost two years now. My wife takes it to work all the time and it has held up well. The only issue has been a cracked lid. One email to Hydrapak with a photo of the cracked lid and a replacement was on the way, they sent two new lids. Hydrapak responded the next morning after I sent the email. In my experience their products are durable and the customer service is first rate.

    • I don’t think it’s a durability concern. It’s that fact that you still can’t get them in most places on earth if you were to need a replacement, compared to a soda bottle.

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