HydraPak 42mm Filter Cap

• Turns a 42mm HydraPak flask into a filter bottle.
• Drink straight through the cap or squeeze into another container.
• No chemicals and no waiting around for tablets to work.
• Flip-top opening is easy to use on the move.
• Small and light enough to forget it is in the pack.

• Thread size: 42mm
• Filtration: Hollow-fibre membrane, removes 99.999% of bacteria such as E. coli and 99.9999% of protozoan cysts (brand testing)
• Lifespan: About 1,500 L
• Flow rate: More than 1 L per minute
• Weight: 57 g
• Cap style: Flip-top
• Fits: 42mm HydraPak flasks and bottles: UltraFlask, SkyFlask, Seeker and Flux
• Materials: BPA-free, PVC-free
• Maintenance: Backflush to restore flow

• Trail runners and fastpackers refilling from streams
• Long days out where water sources are uncertain
• Travel and backcountry trips
• Runners who would rather skip pumps and tablets

Less suited to: Runners who do not already own a 42mm HydraPak flask, as the cap needs one to work. For that, look at HydraPak flasks and accessories.

Plenty of Central Otago and Southern Alps runs pass streams but no taps. This cap lets you top up and drink with a flask you may already carry, rather than adding a separate pump or a pack of tablets. It sits neatly alongside the HydraPak flasks we already stock.