Brand: HydraPak
Category: Running Water Filtration & Treatment
Recommended by Hunter Macy, Founder @ Rendezvu — Jackson, WY
The UltraFlask™+ Filter Cap is an essential accessory for runners seeking a lightweight and efficient way to access clean drinking water on the go. Designed to fit seamlessly with HydraPak’s 42mm flasks, it ensures you stay hydrated with freshly filtered water, enhancing your outdoor experience. 1. Compatible with all HydraPak 42mm running flasks and handhelds for versatile use. 2. High-flow Blaster valve allows for quick and easy hydration without the hassle of unscrewing the cap. 3. Effectively removes 99.999% of E.coli and 99.9999% of parasitic cysts, ensuring safe drinking water. 4. Lightweight and compact design makes it ideal for trail running and long-distance activities. 5. Traditional bite valve design provides a familiar and user-friendly drinking experience. 6. Durable construction ensures long-lasting performance, even in rugged outdoor conditions. 7. Backed by a Beyond Lifetime Guarantee for peace of mind with your purchase. The UltraFlask™+ Filter Cap is perfect for outdoor enthusiasts, particularly runners and hikers, who need reliable access to clean water during their adventures. It excels in various environments, from trails to marathons, and is designed for users of all skill levels. Ideal for warm weather activities, this cap ensures you can stay hydrated without carrying heavy water bottles, making it a must-have for any serious athlete or adventurer.
Price: $43
- Who it's for
- Trail runners, ultrarunners, and field workers who need to refill from natural water sources without carrying heavy filtration gear. Works well for long days where pre-stashing water isn't practical.
- What people are saying
- Hosts consistently praise the minimal weight, ease of use, and ability to grab water on the go from streams and natural sources. The locking mechanism gets specific callouts for preventing leaks when stored in a vest or belt.
- Worth noting
- Compatible with most flasks, not just HydraPak bottles. The straw cap variant is noted as particularly useful for drinking from front-pack bottles without craning your neck during races.
Hunter Macy's review
This thing is unreal. Saves you so much weight. Grab water from anywhere.
Recommended by Hunter Macy, Founder @ Rendezvu
Frequently asked questions
Who is the UltraFlask™+ Filter Cap for?
Trail runners, ultrarunners, and field workers who need to refill from natural water sources without carrying heavy filtration gear. Works well for long days where pre-stashing water isn't practical.
What do experts say about the UltraFlask™+ Filter Cap?
Hosts consistently praise the minimal weight, ease of use, and ability to grab water on the go from streams and natural sources. The locking mechanism gets specific callouts for preventing leaks when stored in a vest or belt.
What should you know before buying the UltraFlask™+ Filter Cap?
Compatible with most flasks, not just HydraPak bottles. The straw cap variant is noted as particularly useful for drinking from front-pack bottles without craning your neck during races.
What does Hunter Macy say about the UltraFlask™+ Filter Cap?
This thing is unreal. Saves you so much weight. Grab water from anywhere.
Why does Hunter Macy recommend HydraPak?
Hunter Macy recommends the HydraPak UltraFlask™+ Filter Cap for running water filtration & treatment. This thing is unreal. Saves you so much weight. Grab water from anywhere.
Is the UltraFlask™+ Filter Cap a good running water filtration & treatment?
Yes — Hunter Macy recommends the UltraFlask™+ Filter Cap by HydraPak as their running water filtration & treatment pick. This thing is unreal. Saves you so much weight. Grab water from anywhere.
More from Hunter Macy's Canyons 100
View Hunter Macy's expert gear recommendations on Rendezvu
What other hosts are saying
12 experts recommend the HydraPak UltraFlask™+ Filter Cap.
Ultralight water filter that conveniently connects right to your HydraPak soft flasks!
Recommended in Fastpacking
John Bruno, Ultra trail-runner, ski mountaineer
Self explanatory: Big thing here is that it locks so I can filter water and put it in a pack or a belt and not soak my kit.
Recommended in High Alpine Running
Tyler Sarkisian, Endurance / Strength Athlete + Coach
carry 1-2 with me so I can always find water. filters just about anything.
Recommended in Trail Run
I try to treat my water from natural sources in almost all areas that I’m exploring. These filters are simple and quick to use with minimal added weight to a regular soft flask.
Recommended in Mountain Running Safety Gear
Makena Morley, Professional Runner (Roads, Trails...)
Absolutely love this filter - it fits on most bottles and is so nice to bring along so I can refill all my bottles on a longer training day when I don't stash aid at my car or house! And you can drink out of it and not worry about getting Giardia!
Recommended in Hydration while running
Compatible with most flasks. Great tool for the trail runners tool kit when you want to go farther.
Recommended in Trail gear I actually use
Jamie Hunyor, Ultrarunner & field botanist
I have two of these—one for long days on the trails in my belt or pack and another in my field bag for going off-trail in my day job as a botanist in the Sierra Nevada. On the trails it saves weight so I can carry less & still stay hydrated. At work, it gives me peace of mind knowing that if something happens & I run out of the water I’m carrying in my pack, I’ll be able to fill from the streams in my survey area.
Recommended in Botany fieldwork gear
These let me use my front pack bottles without craning my neck - They stow nicely out of the way in the Tantrums vest. It's not much, but after 4 hours of bending your neck to drink water, it's the little things.
Recommended in Dirt Run Essentials
Allison Powell, Ultrarunning Coach, Ultrarunning Communnity Leader
This cap was easy to add on to HydraPak bottles and allowed me to simply fill water and go!
Recommended in Tahoe-Yosemite FKT
Joe Corcione, Ultrarunning Athlete + Coach
With a lot of water on the course, I'll be using this filter cap to fill up some on the go!
Recommended in Western States 100M Gear I'll Be Using
Straw caps make drinking so much easier while racing.
Recommended in Run Rabbit 100
