Montane Ultraflask+ Filter Cap

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Fast-flowing, compact, and easy to clean, this filter cap brings flexibility to lightweight hydration setups.

Hydrapak says: 

Run fast, filter faster. The UltraFlask+ Filter Cap threads seamless onto all of HydraPak’s 42mm running flasks and handhelds for a lightweight, straightforward filtration solution. Featuring a traditional bite valve and cap design, runners can drink freshly filtered water directly through the high-flow Blaster valve.

Our Verdict

The updated HydraPak UltraFlask+ Filter Cap is a tidy upgrade for 42 mm-threaded soft flasks, adding a high-flow hollow fibre filter in a package that weighs just 35g. The bite valve is smooth to drink from and self-sealing, which cuts down on leaks when stowed. The included backflush adapter is a nice touch—it makes cleaning simple and helps keep flow rate consistent over time. It’s rated for around 1,500 litres of use, and although it won’t remove viruses, filtration is ideal for most backcountry water sources in temperate regions.

– Reviewed by Ultralight Outdoor Gear

Features

• Fast & Safe Filtration: The intergrated filter removes Escherichia coli bacteria, Cryptosporidium parvum cysts, and Giardia Lamblia from approximately 1,500 liters of water at a rate of >1L per minute.*
• Light and Compact: Minimal design and lightweight materials make this filter the ideal choice for runners. It takes up no extra space when stored or threaded directly onto a flask.
• High-Flow: Easy to drink bite valve auto-seals after each sip, eliminating annoying drips.
• 42mm Thread Compatible: Easily thread the filter onto some of the most popular running softflasks, flexible bottles and water storage containers
• Included Backflush Adapter: Plugs into filter valve and threads onto a HydraPak Stow or bottle of clean water for backflushing the filter to restore its flow rate.

*Effectively removes common waterborne bacteria, such as E.coli (99.999%) and parasitic cysts (99.9999%) per HSF 42.

Specifications

• Weighs: 35g
• Capacity: 500ml / 17fl oz
• Dimensions: 280 mm x 80 mm / 11 in x 3.1 in

Material & Construction

• ABS, POM, Silicone, Hollow Fiber

Help & advice:

• The Ultimate Guide to Water Treatment and Purification
• Time-Saver Guide to Water Purification
• What does BPA Free Mean?