HydraPak UltraFlask+ Filter Cap

Hydrapak UltraFlask+ Filter Cap

A lightweight filter cap that turns any compatible 42mm Hydrapak soft flask into an on-the-go filtration system for trail runners and endurance athletes who want to refill from natural water sources mid-run without carrying a separate filter. Screw it on, fill from a stream, and keep moving.

Why We Carry It
It's the filter solution we recommend for trail runners and ultra athletes who want to run lighter on water by refilling from natural sources without adding a dedicated filter system to their kit.

Highlights

• Filters water as you drink — Integrated filtration built directly into the cap delivers clean water through the bite valve without a separate squeeze or treatment step. Fill from a stream and drink without stopping to filter.
• 42mm thread for direct flask compatibility — Threads directly onto compatible Hydrapak running flasks and handhelds for a clean, simple setup without adapters or additional hardware.
• High-flow Blaster bite valve — Delivers steady, unrestricted water flow that keeps up with the demands of running and hard effort without the reduced flow of a standard filtered cap. Drink at race pace without fighting the valve.
• Eliminates a separate filter system — Replace a dedicated squeeze filter and separate bottle with one integrated cap on a flask you're already carrying. A meaningful weight and complexity reduction for runners optimizing their kit.
• Built for fast refill transitions — Simple cap design keeps refills quick and efficient during races, long efforts, and remote routes where stopping to filter costs time and momentum.

Best for

Trail runners, ultramarathon athletes, and endurance adventurers who want a lightweight, streamlined filtration solution for long runs, races, and remote routes where natural water sources are available and carrying extra water weight is the enemy.

Compatibility Note

Compatible with Hydrapak 42mm soft flasks and handhelds. Check compatibility with your specific Hydrapak flask before purchasing.