Nalgene-Compatible Platypus Wide-Mouth DayCap Bottle Filter Review

The Platypus DayCap In-Bottle Water Filter is compatible with wide-mouth Nalgene Bottles, Hydro-Flask Wide Mouth, Yeti Yonder Bottles, and CamelBak Wide Mouth Bottles. The DayCap is a 0.2 hollow fiber filter that removes Bacteria and Protozoa from natural water sources including Giardia, Cryptosporidium, E. Coli, Salmonella, and Cholera making it an indispensable adjunct to your hiking hydration system. With it, you can turn any popular wide-mouth water bottle into a complete wilderness water filter system.

• Type: In-bottle water filter
• Bottle compatibility: Wide-mouth Nalgene Bottles, Hydro-Flask Wide Mouth, Yeti Yonder Bottles, and CamelBak Wide Mouth Bottles
• Micron Size: 0.2 microns
• Filter Efficacy: Removes 99.9999% of Bacteria, 99.9% of Protozoa (NSF P231 compliant)
• Integrity Test Available: Yes
• Pros: Ease of use, Works with 3rd party bottles, 1000L filter lifetime
• Cons: Not optimal for longer water carries or camping given limited fluid storage; not compatible with wide-mouth soft bottles for squeeze-style operation – use the Platypus QuickDraw filter instead.

The Platypus DayCap has two components – a wide-mouth cap with a drinking spout and a filter element, which is removable and replaceable.

1. The wide-mouth cap simply replaces the cap of your wide-mouth bottle. It has a fold-down cover to protect the drinking spout from dirt and contamination, which is a must-have from my perspective since cross-contamination is so easy outdoors if you’re not careful. The cap also has a handle that’s easy to carry or clip to your backpack.
2. The filter screws into the cap and hangs below it inside the bottle, so all the “dirty” water inside the bottle passes through it before you drink from the spout. Simple. The filter is a standard-looking hollow fiber filter with side perforations allowing water to flow into it when you tip the bottle to drink. It has a minimum lifetime of 1000L, a flow rate of 1L per minute, and separate replacement filters are available. To clean it, you simply fill your bottle 1/3 of the way and shake vigorously to dislodge particles stuck in the filter. This is the same cleaning method used with similar filters like the Befree. 

To refill a bottle with a DayCap, unscrew the DayCap and set it aside with the filter spout in the closed position (to prevent accidental contamination). Fill the bottle from the water source. Screw the DayCap back on securely and wipe down the sides of the bottle to prevent ingesting unfiltered drips.

To drink from the DayCap, simply flip open the spout and tilt the bottle. There’s no need to squeeze or suck provided you’ve presoaked the filter the first time before use. It’s as easy as drinking from a glass of water.

Here are a few cautions when using the DayCap: There’s nothing major, but worth repeating if this is the first time you’ve used an in-bottle hollow-fiber filter.

• Using the DayCap as In-Bottle Water Filter means you will be using your water bottle as a “dirty reservoir” and exposing it to water containing contaminants that can make you sick if ingested without being filtered. The best way to avoid this is to keep the DayCap attached to the bottle between uses.
• When drinking from the bottle, make sure the DayCap is securely attached to the bottle threads and water does not leak through them. If it does, you could potentially consume unfiltered water if it comes in contact with your mouth.
• Do not let the DayCap freeze in cold temperatures because it can potentially damage the filter element. If frozen, conduct an integrity test using the product instructions, or replace the filter element.
• If you get your hands wet when refilling from a wilderness water source, remember that they are “dirty” and potentially contaminated with organisms that can make you ill.
• For long-term storage, the filter can be stored wet, although it’s best to disinfect it first using a diluted bleach solution – see product instructions.

Recommendation

The Platypus DayCap Water Filter is a great add-on to the wide-mouth bottles you already own, including 32 oz Nalgene bottles, Hydro-Flask, Yeti Yonder Bottles, and CamelBak Bottles. The DayCap also lowers the water filter “bar” for day hikers, who will benefit by having to carry less water on hikes and can refill along the way. This is an especially big deal for older hikers since water is probably the heaviest item in their backpacks.

While it is designed for removing bacteria and protozoa from wilderness water sources, the DayCap is also a good solution for everyday use at home or work for removing microplastics and other water contaminants. I particularly like the DayCap because it can be used with other manufacturer’s products, cutting down on the babel of competing filters you have at home that only work with proprietary bottles.

Disclosure: Platypus donated a DayCap for an honest review.