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Hydrapak UltraFlask Speed 600ml - Collapsible Soft Flask Water Bottle for Hydration Vests and Running Packs with Easy Open Cap (600 ml/20 oz), Malibu Blue

TLDR Review: Hydrapak UltraFlask 600ml Bottlex

Item: Hydrapak UltraFlask 600ml Bottlex
Author: ShopSavvy

By ShopSavvy Team

Published: February 2nd, 2026

Pros

•Very durable and reliable, performing exactly as advertised for lonistance and trail running.
•Fits perfectly into most hydration vest pockets and conforms comfortably to the body, minimizing bounce.
•Soft, compressible design reduces sloshing and gets lighter as you drink.
•Convenient bite valve with an extended straw allows easy sipping without removing the flask.
•Wide opening makes adding ice or electrolytes simple and eases thorough cleaning.
•Compatible with various running vests and packs without leaking.
•Lightweight and comfortable for longer runs, including ultras up to 100 miles.
•Easy to clean and dry, suitable for multay use with cleaning tablets.
•Larger capacity than many similar soft flasks, balancing volume and pack compatibility.
•Rollable design allows compact storage when not in use.

Cons

•Bite valve tends to hold liquid inside, requiring removal of the hard plastic piece for thorough cleaning.
•Hard plastic component of the bite valve sometimes fails to nest securely back, risking leaks.
•Bite valve does not lock, which in some cases has led to it popping off and spilling.
•New silicone material reportedly has an unpleasant taste compared to older versions.
•Flip cap hinge can be uncomfortable against the neck and wears down surfaces it contacts over time.
•Some users find the straw placement tricky, with occasional bouncing or pressure against the neck.
•Despite cleaning, some flasks have developed leaks after extended use.
•Flip cap design is less convenient compared to screw caps or simpler closures.

Bottom Line

The Hydrapak UltraFlask Speed 600ml is a solid choice for runners and trail enthusiasts who want a durable, lightweight, and comfortable soft flask that fits well in hydration vests and offers easy access to fluids on the move. Its collapsible design and ease of cleaning are major pluses, but if you’re picky about taste or want a bite valve that locks securely, you might find room for improvement. If you want a soft flask with a more secure valve and possibly a less finicky cap, keep an eye out for alternatives, but overall, this model is a reliable hydration partner for serious runners and long ultras.