I took a look at some screw-top 16 oz beverage bottles to use as an alternative to a large mug for boiling water, and was quite surprised at the performance of these. I would describe them as a whole new category, since these can be dual use cookpot and water bottle. There are some compromises that you should be aware of, so like most dual-use items, you should weigh the shortcomings against the advantages before deciding if these are for you.
There is quite a variety of these in stores with varying weights, from the sub-ounce beer bottles, to the two ounce, beefier energy drink bottles. Two of the four I tested were from a Japanese grocery store (a 0.8 oz. Gatorade-like vitamin C drink and a 0.9 oz. awful green tea drink). The other two are a 1.0 oz. Coors Light bottle, and a 2.2 oz. Vuka energy drink bottle.
Good News
The four bottles I tested had amazing boil times when coupled with a Zelph Budlyte stove: ~4:30 on average for 16 fl. oz. on 15 ml denatured alcohol. I couldn't get the same performance with my Zelph Starlyte, so I imagine only stoves of a certain design work well with these bottles. To fit the narrower bottoms of these bottles, I inserted a 1/2" extension tube in the Budlyte. On the bottle that didn't need the extension tube (Vitamin C), as well as some other pots I tested, the performance was much better with the extension tube than without it, which suggests that the Budlyte stove can be optimized by increasing the pot stand height.
When considering these as dual-use cookpot and water bottle, the performance as a water bottle can't be overlooked. For several days I used the Coors Light and Vuka bottles as part of my daily commuting and office routine, and couldn't get them to fail. These samples were also used to heat water at least a dozen times each, so I would say they're certainly durable for at least a weekend: there was no visible "aging" with either the walls, the neck, or the cap's seal. I also judged the bottles for funkyness, which is a scientific term for a water bottle's inability to ward off saliva-induced bacteria growth. Of course, the heat from use as a cookpot certainly helps remove any funkyness.
One water bottle workflow I didn't try was using it inside a sleeping bag. Imagine taking the bottle off the stove, replacing the cap, and putting it inside the bag. I suppose this is possible, just don't heat the water too much!
Weight Benefit
These bottles can save weight. Let's look at my old setup:
BPL 500 (handle-less), 1.8
Foster's, 0.9
Gatorade (2), 3.4
Total 6.1 oz.
Now swap that Foster's with a Coors Light, and swap those Gatorade bottles with a (fictitious) 1.5 liter, 2.0 oz. water bottle:
Coors Light, 1.0
BPL 500 (handle-less), 1.8
Gatorade 1.5L, 2.0
Total, 4.8 oz.
Woo-hoo! 1.3 oz. savings in weight, not counting the savings in fuel (12 ml vs. 15 ml per boil).
Compromises
- When boiling water, it's hard to judge water volumes less than 16 oz. The narrow opening and opaque walls are the culprits, so if you need to boil less you'll need a separate measuring cup. Likewise, as a water bottle you can't see how much water you have left.
- The bottles are boil-only, so that limits these to freezer-bag meals or to use with a separate pot.
- They all have a tendency to boil-over, but this can be managed.
- Although I could use my small MSR pot lifter on the bottles without damaging the threads, this is an awkward position to pour from as the steam rises directly towards my hand. I suppose a fiberglass wrap would solve this, but I don't know how to make one. Use a glove.
- Most bottles have very thin walls like a beer can. The cautions with handling fragile beer cans applies, and may affect their use as a water bottle, since those are usually stored in outside pockets.
- You can't fit your stove or pretty-much anything else inside the cookpot, so your stove will have to stored elsewhere.
- As a water bottle you'll have to make up for the 1/2 liter shortfall on volume. I don't recommend carrying two of these as the extra ounce or so would be better used for a plastic bottle that holds a liter. I want to couple one of these aluminum bottles with a larger plastic bottle (say 1.5 liters at 1.2 oz.) so I can have my standard 2 liters, but I haven't found one yet.
- I assume the bottles are lined with plastic similar to beer cans. Whether this is dangerous or benign I can't say, so do your own homework if this is a concern. I'm still alive…
- The cap's seal may wear out over time.
- The cap's edge is somewhat sharp, but you can sand the edge down, or just be careful.
- None of the bottles are suitable for use with a Steri-Pen Adventurer, but perhaps the Classic and Journey models will fit the wider-mouthed bottles.
Bad News (and Recommendations)
Most of the bottles I tested have a normal capacity of 16 fl. oz. (the smaller one is 14 fl. oz.). When this amount of water is boiled, it invariably boils-over resulting in a somewhat dangerous condition. I tried all sorts of gizmos and what-not to prevent boil-overs, but found the best solution was to use slightly less fuel so the water temperature would max out at > 200F and < 212F. Among all the bottles, 12 ml of denatured alcohol provided the same ~205F performance. In some cases, the temperature reached 211F, but this was long after the stove's output had subsided. Certainly, if you're boiling treated water, even 190F would be good enough, so I'm content using 12 ml of fuel.
These bottles make for a tall cookpot, with approx 10" of stove and bottle to protect from the wind. Windscreens this tall are awkward and hard to pack, but here are my recommendations:
- The windscreen only has to be about 8" tall. Shorter screens increased boil times, and taller ones didn't help. 8" is also about the height of the bottle's widest part, so the simplest windscreen could be stored by wrapping it around the bottle and holding it in place with a rubber band or Velcro strip. This does detract from water bottle use as the screen adds edges to the bottle which could snag on pocket netting, and bottle has a tendency to slip right out of the windscreen.
- Another idea is to pack the windscreen inside the water bottle. At the right height it shouldn't interfere with drinking or insertion/removal. I decided this wasn't for me as windscreens tend to get slimy and dirty over time.
- At first I didn't have an 8" tall windscreen, so I placed one short one inside the other, kind of like a telescoping antenna, and that worked OK. However, this does require a double-wall bottom to create enough friction to hold the upper in-place.
- I found 1/2" clearance around the bottle worked well.
- I like having a separate mug for drinking, and I like to be able to throw this mug on the stove to efficiently heat smaller amounts of water. We're used to packing cookpots and stoves together, but this isn't possible with these bottles. The mug provides an easy solution, and if you pick the right mug, the two-piece windscreen will fit inside the mug too. I found I could fit the Budlyte stove (with extension tube), windscreen, lid, lighter, scrub pad, Dr. Bonner's soap, and firesteel in a Snow Peak 450 mug. Likewise, I could fit the same items in a BPL 500 mug (placing the stove on its side).
I don't use the bottle cap as a lid. I noticed that whether it was on or off, I got just about the same boil times, so I just leave it off when boiling water. And for all the lawyers out there, let me say now that incorrectly mounting any lid, including the original bottle cap, could result in a catastrophic failure of the bottle if the water is allowed to get hotter than 100F.
Specific Bottle Variations
The lightest 16 fl. oz. bottle is the Vitamin C bottle at 0.8 oz. with (and without) the cap. This bottle is also unique because it has a pop-top bottom, minus the pull-tab (think upside-down soda can). I'm not sure why the bottle has this design, but I was worried that heat would cause separation of the bottom. Fortunately, this didn't happen after several boils, and I would think it would take a lot more heat to cause a failure. Because there is a raised rim, this is the only bottle that completely raises the bottom off the ground–if that's of interest to you. This bottle was also the most difficult to fill because of its narrow opening, and even judging the 16 fl. oz. mark was harder than the others.
The lightest bottle is the green tea bottle, but its capcacity is only 14 fl oz. It doesn't have silk-screened graphics but instead a shrink-wrap label that you might see on a plastic bottle. However, once this is removed, it reveals an unadulterated and attractive aluminum surface. I was wondering if this would be better for shorter trips or simply for day use, but although 12-14 fl. oz. might be fine for boiling water, it starts to be less effective as a water bottle.
The sturdiest bottle is the Vuka, but it does weigh 2.2 oz. However, you get a fairly durable bottle compared to the others; I doubt this bottle would be damaged by springing branches and thorns. (Most likely, your mesh pocket would get far more damage.) It's also the only bottle with a plastic insert for the threads, which I feared would melt easily. I was happy to see that insert didn't melt, and after several boils, there is no deformation or delamination from the bottle at all (I tried removing them when the bottle was hot with a pair of Vise-Grips, but they didn't budge). Its extra thickness didn't really affect boil times at all, so if I had to choose one bottle for a week or more, this is the one for me. As a bonus, these bottles come in several exciting colors.
Future
I see these bottles as part of a minimalist cookset, where boil-only is the norm, and using a 16 fl. oz water bottle (combined with 1 or more plastic bottles) is manageable. For the price, they're easy to try out–just keep in mind the compromises listed above, and that your stove may not work well with them. I will bring one with me on my next trip and see if I like it in the field.
I'm sure these bottles will catch-on among some in the Community, and perhaps we'll see stoves designed for them in the near future. I guess a Caldera Cone is possible, and that may eek out a few more joules from the fuel. I would like to see a "Coorslyte" stove that fits these bottles, as well as a Starlyte potstand accessory to retrofit existing Starlyte stoves (may need a different height to perform well). One thing's for sure: if you want to try these bottles out, get them while you can; as we learned from Heneiken there's no guarantee they will make them forever…
Database
Coors Light
~$10 for a 9-pack
1.0 oz. with cap
17.5 fl. oz max.
1.2" opening
Vitamin C
$2.50 in Japanese supermarket
0.8 oz. with cap
18.75 fl. oz. max
0.78" opening
Green Tea Beverage
$2.50 in Japanese supermarket
0.9 oz. with cap
15.5 fl. oz. max
1.2" opening
Vuka Energy Drink
$2.50 in supermarket
2.2 oz. with cap
17 fl. oz. max.
1.2" opening
