This photo shows the humangear capCAP+ 2-in-1 water bottle cap.

Humangear capCAP+ Water Bottle Cap Review

- Field-tested -

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The humangear capCAP+ is a 2-in-1 wide-mouth water bottle cap accessory that’s designed to fit many ‘industry standard’ water bottles. It lets you keep the versatility of a wide mouth water bottle but lets you drink from a much smaller bottle-style cap instead.

It seems like a small thing, but for me, the humangear capCAP+ has led to a meaningful incremental improvement in my life: I’m drinking more water than ever before. The capCAP+ is basically one of those great products that reduces friction against a frequent daily activity.

I appreciate that.

Humangear capCAP+ Review

This outdoor gear photo shows the humangear capCAP+ water bottle cap.
Wide for ice and cleaning, narrow for easy drinking!

Because this small, inexpensive piece of gear delivers a value far beyond its humble price point, I’m willing to take the time to tell other people about it and reward humangear with a bit more attention.

I bought my first capCAP a decade ago, and I still have two first-generation versions (without the “+” in the name) still in use on standard Nalgene water bottles. The problem with the original capCAP, however, is that it didn’t seal very well on stainless steel water bottles. The new capCAP+ uses two silicone gaskets that create waterproof seals on many bottles, including water bottles made by Hydro Flask, CamelBak, Nalgene, GSI, and humangear.



Today, lots of people use double-walled stainless steel water bottles. These insulated stainless steel water bottles tend to have wide mouths to let you easily add ice. They keep contents cold all day long. The trouble is, some of these relatively expensive water bottles have lousy caps. Sure, you can drink from a water bottle like you would from a standard drinking glass, but if you’re doing it from a moving vehicle, there’s a good chance your driver will hit a bump at some point, resulting in some spillage.

If you’re like me, you’d rather drink out of a narrower bottle-style opening from your water bottle. The capCAP+ gives you the best of two worlds: You can use a wide-mouth bottle that’s easy to clean and easy to use with ice . . . but also drink from a narrower opening.

For me, it makes a big difference and the result is that I drink more water.

The Small Cap

This photo shows the humangear capCAP+ open on a stainless steel water bottle.
The cap tether has a tab and port that lets you keep the cap out of the way when drinking.

The key to the capCAP+ is the inclusion of food-grade silicone gaskets to make sealing your bottles easy. The small cap has a rubberized coating that’s easy to grip. The small spout is a perfect size and shape — it’s tall enough for room for your nose, wide enough to deliver plenty of water volume when you want to drink fast, and thick enough to feel solid. Humangear did a very nice job with the ergonomics here.

In addition to the silicone seals that let the capCAP+ work with more bottles, human gear added its new CapKeeper notch system to let you stow the small cap out of the way when you want to leave the bottle open and drink frequently.

Personally, I rarely use this feature. What I do is this: When I open the small cap to drink, I automatically fold the small cap over so that one finger holds it down by the tether portion while I drink with one hand. I don’t think about this anymore — it’s just an automatic habit.

Shop the humangear capCAP+ at Cabela’s! 

No Metallic Taste

One benefit of the capCAP+ is that it doesn’t impart any taste at all. It’s PC-free, BPA-free, and Phthalate-free. For me personally, when I directly directly from a stainless steel water bottle, I experience a faint metallic taste. When I use the capCAP+, this metallic taste disappears. I didn’t realize I appreciated that until I recently drank from my water bottle without the capCAP+.


Compatible Cap

This photo shows the underside of the humangear capCAP+.
Each portion of the capCAP+ now has a food-grade silicone gasket for tight seals.

I’m not sure there is an actual “industry standard” wide mouth bottle opening, but many bottle brands make wide mouth bottles with the same size so that caps can sometimes fit other bottles. The capCAP+ works with Hydro Flask, Nalgene, CamelBak, GSI, and humangear wide-mouth water bottles.

The humangear capCAP+ website has a confirmed capability chart at the bottom of the page if you’re interested.

The reality is, the capCAP+ is a relatively inexpensive purchase, which makes it one of our favorite inexpensive gifts for outdoor enthusiasts.

In fact, it’s in our guide to 20 Camping Stocking Stuffer Gifts Under $20. Either way, if you’re still reading this, you should just buy one already and see if it fits your favorite water bottle. If it doesn’t, buy a rugged 32 oz Nalgene bottle and use it as a backup water bottle.

capCAP+ Drawbacks

This photo shows where the capCAP+ started to break after a year of frequent use.
I tend to use one finger to fold down the cap tether. After a year of frequent use, it started to break.

After a year of use, the repeated bending of the small cap plasticy tether where I fold it down and hold it while drinking wore out. For a while I just trimmed the edges with sharp scissors and used it as a non-connected cap. That started to annoy me. I realized this was silly: The capCAP+ works so well for me, I should just buy a new one and use it until it breaks. The whole point is to improve my drinking water experience and remove speed bumps that slow healthy hydration habits. So I bought another one. And it was well worth it. Will it wear out for you? Depends on how often you use it. I used mine everyday while drinking 1-3 bottles of water for a year . . . and I bent the tether every time.


Favorite Water Bottle: GSI Microlite 1000 Twist

This photo shows the GSI Microlite 1000 Twist Water Bottle.
The lightweight insulated GSI Microlite 1000 with the capCAP+ is my daily driver water bottle.

My favorite water bottle is the GSI Microlite 1000 Twist. It’s a great water bottle because it’s a lightweight stainless-steel double-walled insulated water bottle that keeps ice water cold. It’s lightweight, too. At 13 ounces, I’m willing to load it up with ice and water and pack it everywhere I go.

For comparison, YETI makes a 36 oz Rambler Bottle with a Chug Cap — a system similar to the capCAP+ 2-in-1 cap solution. I liked the idea quite a bit, but I didn’t want to pack around a heavy-duty water bottle that weighs 20 oz empty. Plus, it’s a bit bulkier than a I wanted.

I considered the 32 oz Wide Mouth Hydro Flask bottle, which weighs 15.2 ounces — not bad. And I considered the excellent 32 oz Hydro Flask Lightweight Wide Mouth Trail Series bottle weighs just 11.8 ounces — even better, right? Not for me in this case beause the lightweight Trail Series is too tall for everyday use. I like a shorter, wider 32 oz water bottle. Picky, I know. Also, the Trail Series doesn’t have a rubber bottom and Hydro Flask doesn’t make a silicon boot accessory for it.

The 33.8 oz GSI Microlite 1000 Twist is the size I like. At 3.62″ wide, it’s very close to the width of the standard 3.55″ wide 32 oz Hydro Flask bottle, which fits the Hydro Flask Medium Flex Boot. This silicone base makes the bottom of your water bottle a bit cushioned and grippy. I was going to buy one and try to get it onto the GSI Microlite 1000 Twist water bottle, but, as it turns out, the GSI bottle has a built-in rubber base that you don’t see in the GSI product photos. It’s nice and grippy on any surface.

The point is, I’ve used a GSI Microlite 1000 Twist water bottle with the humangear capCAP+ every day for the last year. I’m a fan of both — and the healthy living result is that I drink more water.

You might like both, too.

Get the Gear:

humangear capCAP+
Wide for ice and easy cleaning, narrow for easy drinking!
Fits many 'industry standard' wide mouth bottles
Overall ergonomics and design is excellent
Repeated deep bending of the cap cover tether can lead to breakage over time (but only if you bend it with your finger while drinking)


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