HydraPak Ultraflask+ Filter Cap 42mm

HydraPak UltraFlask+ Filter Cap 42 mm

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Filter the water – without slowing down

The HydraPak UltraFlask+ Filter Cap 42 mm is a compact and lightweight water filter cap , designed for running, hiking and adventures where quick and easy water purification is essential. The filter cap screws directly onto all HydraPak products with a 42 mm thread , allowing you to drink safely filtered water directly from your soft bottle – without additional hoses, pumps or external filters.

Efficient and safe filtration

The filter uses hollow fiber technology and is certified to the HSF 42 standard . It removes:

99.999% bacteria , including E. coli

99.9999% parasitic cysts , such as Giardia and Cryptosporidium

The filtration capacity is up to approximately 1,500 liters of water with a flow rate of over 1 liter per minute , making it suitable even for intensive use during long shifts.

Drink immediately – fast flow

The UltraFlask+ Filter Cap features HydraPak's Blaster™ bite valve , which delivers high flow and automatically closes after each sip to prevent drips. You can drink directly through the filter , just like a regular soft drink bottle, making it ideal for trail running, ultra races and fast mountain hikes .

Light, compact and always ready

Weighing just 36g, the filter cap adds minimal extra weight and can remain on the bottle even when not in use. The minimalist design means no extra space is required in the pack – the filter is always ready when you need to refill from streams, lakes or springs.

Easy maintenance in the field

The filter cap comes with a backflush adapter , which allows the filter to be cleaned and flow restored by backflushing with clean water from a HydraPak bottle.
Important: The filter should not be frozen , as ice can damage the hollow fiber membrane – wear it close to your body in sub-zero temperatures.

Features & Benefits

Ultra-light filter cap – only 36 g

Filters water directly when drinking

Removes bacteria and parasites (HSF 42)

High flow (> 1 l/min)

Blaster™ bite valve – drip-free function

Fits all HydraPak products with 42mm thread

Backflush adapter included – easy maintenance

Minimal packing volume – perfect for lightweight trips

Technical specifications

Type: Water filter cap

Thread: 42 mm

Weight: 36g

Filtration technology: Hollow fiber membrane

Capacity: approx. 1,500 liters

Flow: > 1 l/min

Materials: ABS, POM, silicone, hollow fiber

Compatibility: HydraPak UltraFlask, SkyFlask, Stow, Seeker, Flux, etc. (42mm)

Care: Do not freeze; backflush for cleaning

NOTE: Filter cap only – bottle not included

Suitable for

Trail running, ultra-running, fast mountain tours, hiking and emergency preparedness – for those who want reliable water purification with minimal weight , without carrying separate filter solutions.