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Winter Hiking, Hydration, and Insulated Water Bottle Jackets

Drinking plenty of water can be difficult when your head is covered in the cold, so prehydration is key.
Drinking plenty of water can be difficult when your face is covered with a winter balaclava, so prehydration is key.

Whenever you go hiking, it’s important to stay properly hydrated. This is especially important for winter hiking when even mild dehydration can cloud your judgment and reduce your energy level.

In winter, water loss occurs through perspiration and respiration. While you can regulate your perspiration rate by slowing down your pace, most people are not even aware that they lose water through respiration.

When you exhale, your breath transports the moist warm air in your lungs to the drier air surrounding you. If you have a mustache like me, this process is very apparent from the icicles that form on it.

Prehydration for Winter Hiking

I always make a point to prehydrate before I go hiking. If my winter hiking partner and I are driving to the mountains for a hike, we each drink a liter of water before we hit the trail.

This is especially important in winter when the rate in which you lose water can exceed the rate in which your body can absorb water.

Normally, people lose anywhere from 0.5 to 1.5 liters of water per hour when hiking strenuously. Since your body can only absorb a liter an hour, not prehydrating puts you at risk of becoming dehydrated and staying that way during a strenuous hike.

Drinking Throughout the Day

It’s important that you keep drinking water regularly during a winter hike to stay properly hydrated. If you normally use a hydration system during the rest of the year, it can be difficult to adapt to its absence in winter. I counter this by always taking a sip from one of my insulated water bottles when my hiking partner stops to catch her breath, checks her maps, adds or removes a layer, or stops to look at a bird. Once you get into this habit, staying hydrated in winter becomes second nature.

Winter Hiking Water Bottles and Water Bottle Insulation

Hydration bladders and hoses freeze in winter, even insulated ones. You’ll want to carry wide-mouth 1 liter bottles instead, because the lids are less likely to freeze and they’re easier to open while wearing gloves. The best winter water bottles are wide-mouth Hunersdorf bottles with their distinctive yellow cap or milky white wide-mouth Nalgene HDPE one-liter bottles because they don’t crack like the clear ones when they get cold or you pour boiling hot water into them. Don’t even think about bringing a metal bottle on a winter hike. You’ll be laughed at before you’re kicked off the hike.

40 Below Neoprene Water Bottle Insulators
Neoprene Water Bottle Insulators

When you fill these bottles with water you want it to be as hot as possible, so boil it on the stove or in the microwave beforehand. Once filled, you need to insulate the bottles, so the water stays hot as long as possible during the day. Turning them upside down will also prevent the caps from freezing shut. When purchasing winter water bottle insulators, it’s imperative that you buy ones that insulate the lid of the bottle and not just the sides.

Try to find water bottle insulators, also called “parkas” or “jackets” that you can clip to the outside of your backpack with a carabiner since this makes it much easier to keep drinking during the day. You won’t drink as much if you have to stop and pull a bottle out of your pack.

Post Hike Hydration

One of the first things I do after a winter day hike is to drink another quart of water and eat some food. This keeps me alert when we’re driving home.

If I’m backpacking in winter, I do the same thing, except we have to melt snow first with a stove. I also take a quart of hot water to bed with me and sip it when I wake up during the night to pee. Staying hydrated is important at night because it helps the digestive processes that keep you warm after a big dinner and ensures that you don’t wake up mildly dehydrated the next morning.

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  1. I have some Liberty Mountain water bottle boots. They are not exactly what I want because they don’t tightly seal at the top. Much prefer the 40 below ones I have that completely seal the bottle. I haven’t used the OR bottle boots, because they are a bit pricey, comparatively..

    • You can save some gear weight and money by carrying your extra bottles buried in your pack wrapped in your puffy insulation. It’s actually nice to feel the warmth radiating through the back of your pack on a cold day. If you do this though, you have to make damn sure they dont leak. Keep one insulated bottle on the outside of your pack though. I clip mine to my hip belt so it’s super easy to reach. It’s really import to keep the cap insulated because it will be the fist part to freeze.

      • I’ve learned to turn them upside down. It’s not so bad when the bottom of your water bottle starts to freeze. The cap will still work.

      • I take one larger bottle in my pack insulation, and one smaller bottle in my coat as I hike or ski (depending on whether liquid water is still available) – this saves more weight because neither bottle needs it’s own insulation, the water in my coat is that much more handy for drinking, and stays warmer next to my belly. If I’m hiking in an area with flowing water and don’t need to melt snow, I find having the cold water next to my belly is ok if I layer properly, and (I think) it has actually enabled me to reach a higher level of exertion without sweating. Meanwhile the heat I generate goes toward warming the very cold stream water, which makes it easier to drink.

      • Another form of water loss in winter that increases is ‘insensible perspiration’ – the amount lost by the relatively moist body to the relatively drier air of winter, without actually sweating. This type of water loss is higher in winter, and is why lips become chapped, etc. It also means you have to drink more water than you normally would (i.e. under the same level of exertion in a more humid environment) to keep hydrated. You can be fooled when you wear very breathable clothing too, because both insensible and sensible (sweat) perspiration will leave your layers more quickly to the drier air, making you feel as if you are dry and not losing any water….when in fact you are often losing more than you normally would in warmer weather. The dry air acts like a sponge, essentially. This is one of the rationales for using vapor barrier clothes while active in very cold temps – though I don’t yet have experience there. Applying chapstick to lips is essentially using a vapor barrier to help avoid more moisture loss, and technique can be used elsewhere.

  2. It won’t make a huge difference, but dissolving any kind of electrolyte replacement powder, dehydrated coconut water, sugar, etc. will lower the freezing point of water and delay freezing a bit. Plus you get the benefit of some extra carbohydrate (calories!) from just drinking.

  3. If the water in your bottle starts to freeze, either drink it quick or pour it out of the bottle. Its better to loose some water than having to thaw a full bottle of ice.

    • Turning it upside down is even better, so the cap won’t be frozen shut. It’s easy to unfreeze anything with hot water, which you’d make when melting snow to make more water, if camping.

  4. I agree prehydration is so key! I aim for 32 ounces during the night and 32 on the drive to the trailhead. I do have some different feelings about using insulated parkas though. Contrary to what’s most common I believe carrying water bottles inside a pack is better than clipping them on the outside utilizing a “Parka”. First if they are swinging that actually effects balance and effort over a long hike. If they must be outside the pack secure them from swinging. Second if packed inside the pack against your back they will never freeze and the dense weight is better distributed than hanging off the far outside area of a pack. This let’s me skip ever needing a parka. In real cold instead of small sips all day I drink about 8-10 ounces at any pit stop. When it’s that cold keeping on the move with less water breaks leads to greater efficiency.

    • I like having a bottle carabinered to my hip belt and the rest stowed in my pack. Look at it this way. If you hike in a group in winter, your transition times are greatly increased if people have to open their packs are breaks. Having one bottle out always helps speed things up…you just swap bottles when you need a new one…and it keeps people better hydrated (especially beginners) because the water is close at hand.

  5. Totally a side note to the topic: As with the first photo illustrating this post, i notice that many photos containing a significant area of snow are often underexposed, not just in this instance, but on other websites and sometimes even in print. Instead of appearing near white, the tone of the snow is gray, and darker tones in the image are muddy (too dark to show much detail).

    I suspect the reason for this is that the camera was set on some kind of auto-exposure mode. A camera’s meter is designed to average all the tonalities within the frame to average out to a middle gray tone; that is, a tone that reflects 15–18% of the light that strikes it. Imagine a gray scale from white to black; this tone would be at the midpoint.

    This works well enough for most “average” scenes that contain a range of tonalities, but fails when the overall scene is especially bright (snow) or especially dark (a person agains a black wall, for example). In each case, the camera is averaging all the tones to produce a middle gray; thus, bright scenes are underexposed, and dark scenes will be overexposed.

    Most cameras have some sort of manual exposure compensation function when in auto exposure mode. The solution to this problem is to add 1–2 stops of exposure for bright scenes like snow, and reduce exposure by 1–2 stops for scenes with a predominance of dark tones. Exactly how much compensation is required will depend on the specifics of the scene. Another solution is to shoot in manual mode, and take selective spot readings, but that’s a longer discussion.

  6. One more thing… Does anyone have an authoritative answer to whether it’s necessary to actually boil melted snow—or filter or treat the melt water—to ensure microbial safety? A cursory search of the Interwebs brings up inconclusive information; lots of “it depends” centered on observed snow contaminants. But, since any precipitation can nucleate on most anything, and given there there’s all kinds of “stuff”—biological and otherwise, microscopic and larger—coursing around the atmosphere, it would seem like not boiling or treating would represent at least some risk, in most cases.

    • If the snow is fresh and clean it’s not an issue. However, nasties can live in freezing conditions for a long time. So if it is an area frequented by animals, or shallow snow I’d still be careful. Also, algea and bacteria can grow in snow.

      Filters don’t work in freezing weather. The thin film of water freezing in the filter element can damage it. Same problems as bladders and hoses. The bite valve is the first thing to freeze.

  7. I put wide-mouth bottles into wool socks for insulation. If they go outside my pack, I cover them with the plastic bag my newspaper comes in, to keep the socks dry. The tube-shaped bag fits the sock-covered bottles almost perfectly. The bonus is that both the socks and plastic bag can have multiple uses if needed, such as back-up mittens, which saved a buddy’s hands on one trip. This expedient is, however, for conditions that are less severe than Phillip encounters in places like the White Mountains.

  8. If you don’t mind the weight, an insulated Hydroflask significantly out performs the insulated bottle holders. The draw back is that it keeps the water so hot, that it’s not drinkable until later in the day. My son did a test starting with boiling water and after 6 hours in 32 degree temps, the water in a 24 oz Hydroflask was 130 degrees and inside an OR insulator it was only 77 degrees. Good for a backup to use later in the day.

  9. Thanks for you insight. You state “Don’t even think about bringing a metal bottle on a winter hike. You’ll be laughed at before you’re kicked off the hike.” I’ll bite and ask why? I take a Hydro Flask with me for hot tea of coffee on the trail all the time. I love them. What am I not getting here? Thanks.

    • A thermos is different than a metal bottle. But personally, I still wouldn’t carry one. I’ve found and observed that people can’t drink the liquid in them because it stays too hot. I also wouldn’t want to carry the extra weight.

  10. Hey Philip,

    I saw on Liberty Mountain’s website that it said the Hunersdorf bottles have been discontinued. Any info about this? Looks like there’s still 1.5 and .5 L bottles available but no 1 L. Seems like they’ve been sold out on 40 Below’s site for awhile too.

    Is the only drawback to the Nalgene the lid keeper strap? Would they work the same if you just cut that off? I suppose the grip on the Nalgene isn’t as knobby as the Hunersdorf which could make getting a good grip trickier.

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