42mm Filter Cap - Water Filtration Accessory - Fast Flow - Perfect for Hiking, Endurance Sports, Camping, Travel, and Emergency Preparedness

I’ve used the HydraPak 42mm Filter Cap on multiple trail runs and backpacking trips, and it’s quickly become one of my favorite pieces of gear. The fast flow rate makes it super convenient...you don’t have to wait long to fill up or squeeze hard to get clean water. On long runs, I’ve been able to scoop water from streams and keep moving without slowing down too much. The design is simple and lightweight, and it pairs perfectly with my HydraPak soft flasks and reservoirs. I really appreciate how compact it is, easy to stash in a pocket or side pouch without adding bulk. Even after repeated use, it still works smoothly and hasn’t clogged up. Overall, this filter is reliable, quick, and perfect for anyone who wants a hassle-free hydration solution on the move. It’s a must-have for trail runners, hikers, and backpackers looking for a lightweight water filter that just works.

Great filter, easy to use, I flushed multiple times before first use; I avoid funny smell/flavor by storing this in open air in the cupboard, keep the filter in water at all times on the trail, and not drinking directly from the spout

I use this with the 4L seeker for backpacking and I love it. Just fill it up when ever I am near water and fill up my nalgene or boil pot when ever I need water. This replaces my 3L water sleeve and removes the need to pump/filter water to refill my reservoirs. Not I just filter water when I need it. It filters pretty fast, but I have not tested yet with murkier water sources yet. Had good water sources this year in the back country.

Hopefully HydraPak is reading this. Love the idea and this filter flows water well. I've used it on 3 camping trips so far, 3-4 days each, and on the last trip I noticed the cap is cracking. The end that locks the cap closed is cracked and a small bit of material is missing that wasn't when new. The center top of the cap has several cracks in it. The filter is good but would be much much better if it lasted longer. That is the only reason for a lower rating here. A cracked cap renders the filter contaminated and worthless for its intended purpose and, thus, unusable. Update: I submitted a claim for service to HydraPak and they came through with a warranty replacement of the filter. Received the new replacement filter cartridge earlier this week. I will see how it performs during the next 2 camping trips in September but I do really like this system so far.

We used this with a large rubber water "flask" while traveling abroad to help avoid gastrointestinal issues. We used it with macroscopically clean water - microbial contaminants were likely present, but we did not use muddy/sandy water from a stream for example. We used the large bag + filter to fill smaller containers. Adding a small amount of positive pressure by squeezing the bag, flow was fairly quick. It was also easy to set the bag on a shelf and then open the valve to wet or rinse toothbrushes, rinse out drinking containers, etc.

Much higher flow rate compared to the knockoffs

Great filter

Used once, worked great! Sadly I lost this AND the hydrapak flask they were attached to while bending over to wash dust off my face in a mountain stream outside of Santiago, Chile. I heard a plop, then saw it rushing downstream. I tried to catch it at the bottom of the trail, but wasn’t fast enough. I’ll buy another when I need it later this year.

Works exactly like the Katadyne befree, fits all hydrapak bags. Used it in the PCT and loved it.

Great filter. Used for 20+ days in the backcountry this year. Filtering mostly clean creek water most of the time. Flow rate is excellent. Would recommend.

This filter has made the hydrapak 2L flexible bottle even more versatile on our multi day hikes.

Es un filtro muy bueno y aunque no tiene tanto caudal como el katadyn befree cumple igual de bien. Además me gusta más este por su tapón (motivo por el que prefiero este al katadyn). Nunca se te va a abrir por accidente, no entra suciedad y se ve muy resistente. Yo he estado bebiendo de un charco en una pista forestal durante un día con esto y no he tenido ningún problema Combinado con la botella hydrapak flux tienes un equipo de filtración perfecto. No tienes que mojarte la mano pues tiene un asa para coger agua de donde sea. Como es medianamente rígida se aguanta de pie y es super duradero. Lo único malo es el sabor a plástico que tienen todas las cosas de plástico flexible como camelbaks y demas... Recomiendo darle unos cuantos lavados con bicarbonato, se reduce mucho el sabor aunque nunca desaparece. 10/10

こちらのHydrapakの42mm FILTER CAPは、 mont-bellの2024年版Flex Water Pack（旧版ではない）とシンデレラフィットです。 これで野営しても沢から水を汲んで浄水して飲めます。 また、セット後はmont-bellのパックと本品のキャップがグレー同士で色合いがいい。 スイスのフィルターキャップは青の意匠面が出るので野営には「ん？」となるので、 こちらの組み合わせの方がおすすめです。