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.
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 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.
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.
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