Staying hydrated on the trails just got a little smarter, and a whole lot simpler when it comes to 1.) running out of water, 2.) seeing a questionable water source and 3.) saying to yourself "shall I?".

The HydraPak UltraFlask+ 500ml is a soft flask for running that does more than just carry water.

With its integrated, screw-on hollow fiber filter, this new design lets you sip safely straight from streams, lakes, or refill stations without the need to carry extra water or complicated filtering gear.

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What is the HydraPak UltraFlask+?

HydraPak took their trusted 500ml soft flask and added a minimalist filter that removes 99.999% of bacteria (like E. coli) and 99.9999% of parasitic cysts (like Giardia and Cryptosporidium). It filters water as you drink—no waiting, squeezing, or setup needed.

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This lightweight setup (just 2.3 oz / 65g) is ideal for trail runners, fastpackers, and minimalist adventurers looking to shed weight without sacrificing safety.

The flexible bottle compresses as you drink, preventing annoying sloshing, and it fits securely into most hydration vest pockets thanks to its soft, vest-friendly silhouette.

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Key features at a glance

  • Price: $50 from Amazon.com
  • Filtration on the go – Hollow fiber membrane filters >1L per minute, effective for up to 1,500 liters
  • Secure grip – Grippy sides make screwing on/off the filter easy, even with cold or wet hands
  • Vest-ready fit – Designed to conform to larger front vest pockets for bounce-free carry
  • 42mm wide-mouth opening – Easy to refill at creeks, aid stations, or kitchen sinks
  • Self-sealing bite valve – No drips, even when stashed or squeezed
  • Backflush adapter included – Keep your filter flowing with a simple clean-out after longer missions

A smarter way to hydrate

Instead of choosing between bulky bottles and uncertain water sources, the UltraFlask+ simplifies your loadout.

Use it solo for shorter runs or pair it with a reservoir for longer adventures.

The built-in filter means you can top up from natural sources mid-run, making this a versatile tool for both daily training on remote trails and multi-day efforts where water stops are few and far between. It’s a clever upgrade to the gear you already use.

Shop the UltraFlask+

The HydraPak UltraFlask+ 500ml is available now for $50 at Amazon and comes with HydraPak’s Beyond™ Lifetime Guarantee.