Platypus DayCap In-Bottle Filter Review

Publication date: 10 Apr 2025

CampingGearOther

If you’re spending multiple days out on the trail, you know clean water isn’t just a convenience, it’s a necessity. For many European trails, you’ll stay at, or at least stop at, huts along the way. However, for hikes where you’re out in the backcountry with no water refill stations, filtering water is a huge consideration.

However, the gear we carry to get that water clean can sometimes feel like more effort than it’s worth. The Platypus DayCap In-Bottle Filter is the kind of tool that quietly solves a lot of problems. It’s small, light, and fast—exactly what you want when you’re filtering water every few hours. I brought it with me to Yosemite National Park for a four-day hike, and it quickly became one of those items I didn’t want to hike without again.

Editor

Katie Mitchell

After a whirlwind of 8 years on the road (and trail!), Katie has hiked the Camino Frances, the Peaks of the Balkans, the Fisherman’s Trail, and extensively in the United States. She is an avid trail runner and now lives in Colorado where she plays in the mountains in her free time. You can follow her adventures on Instagram.

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Testing the DayCap In-Bottle Filter

Yosemite is incredible, but it also keeps you on your toes. The water sources are reliable, but scattered, and the elevation and mileage mean you’re drinking a lot more than you think. On this trip, we hiked for four days, cooking at camp, refilling at streams, and staying on the move. I didn’t want to waste time with slow filters or carry more water than I needed to. That’s where the DayCap really stood out.

The biggest win for me was the speed. Filtering water with the DayCap was as simple as filling up my bottle and sipping. No waiting around, no squeezing, no backflushing, no extra moving parts to lose. It was reliable every time and worked fast enough that I never had to pause long.

I also appreciated how it just fit into my system. I didn’t need a special bottle or separate reservoir. I could use it with a standard wide-mouth bottle, and it didn’t take up any more space than a regular cap. That meant more room in my pack and less weight on my back. The Yosemite terrain is demanding, and saving space and weight made all the difference.

And the water? Tasted clean, no strange aftertastes or questionable smells. After a long climb, there’s nothing more satisfying than taking a deep sip from a cold stream and knowing you’re not risking your stomach for it.

About Platypus

Platypus is part of the Cascade Designs family, a Seattle-based company that’s been making backcountry gear since the ’70s. They’re behind some of the best-known names in outdoor gear: MSR, Therm-a-Rest, and Platypus all fall under their umbrella. What sets Platypus apart is their focus on lightweight, minimalist hydration systems that actually work.

They’re not chasing gimmicks. They focus on usability, packability, and real-world function. Platypus also manufactures many of their products in-house in the USA. That means tighter quality control and more transparency in their materials.

About the DayCap In-Bottle Filter

The Platypus DayCap is a small screw-on filter that attaches directly to wide-mouth bottles (like Nalgene). It uses a hollow fiber filter that removes bacteria and protozoa, which covers most of what you’ll run into in water sources. It filters while you sip—no pumping, no waiting.

There’s a flip cap on top to keep the drinking spout clean, and the cap threads are well-made. There’s no leaking, even when the bottle gets jostled around in your pack. It’s rated for up to 1,000 liters and weighs about 31 grams. That’s less than most protein bars!

It doesn’t filter viruses, so it’s not meant for seriously compromised water sources, but for alpine and backcountry hiking where you’re sourcing from flowing streams and lakes, it should do exactly what you need.

And unlike some filters that clog up quickly or demand constant maintenance, the DayCap doesn’t need anything from you during your trip. Just screw it on and go.

Specifications

Platypus in-bottle filter
Filtration	Tested to EPA & NSF guidelines for the removal of 99.9999% of bacteria and 99.9% of protozoa
Weight	0.07 kg
Filter media	Hollow fiber
Materials	Plastic
Flow (L/min)	1 liter per minute
Country of origin	Made in the U.S.A.

pro's

Lightweight and compact

Fast filtering

No extra gear needed

Great for shorter trips

con's

Doesn’t filter viruses

Not compatible with all bottles, only wide-mouth

Lower filter lifespan

No pre-filter

Conclusion

The Platypus DayCap In-Bottle Filter is one of those pieces of gear that earns its place fast. On my Yosemite hike, it gave me clean water without the hassle, didn’t take up room in my pack, and let me spend more time moving and less time filtering. If you’re hiking in areas with decent water sources and want something lightweight and easy, the DayCap is a smart call.

Platypus DayCap In-Bottle Filter Review

Specifications

Conclusion

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