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How to Keep Your Water from Freezing

Lugging around frozen water is no fun! Here are some tips for keeping your water from freezing, resupplying water, and staying warm at night.

If you want to really enjoy winter backpacking, one of the first skills you need to master is your water management. This is both about staying hydrated and staying warm. It may seem like a minor thing to have your water freeze in a plastic bottle, but if you allow this to happen, it is one of those small things that can spiral into big problems. You don’t want this to happen. So let’s start with the basic gear necessary for managing your water.

Gear for Water Management

Recommended winter gear for water management consist of three components, storage bottles, a stove system, and a cooking pot for melting snow:

1. Water storage:

  • Nalgene bottle (32 fl. oz., weighs 6.2 oz.)
  • Small Nalgene bottle (Optional, 16 fl. oz., weighs 6.2 oz.)
  • Thermos/metal flask (18 fl. oz., weighs 11.1 oz)

2. Stove system:

  • Stove (liquid fuel recommended for below 20º F)
  • Firestarter (flint and/or lighter and matches)
  • Fuel (a full canister or an 11 fluid oz. fuel bottle. 11 fluid ounces is usually sufficient for a weekend, but I often take 20 oz. in anticipation of someone else needing help with water.)
  • Stove repair kit (if you use a liquid fuel stove)

3. Cooking pot:

  • Pot large enough for melting snow (I use the Snow Peak Trek 1400 Titanium Cookset, 7.4 oz). This should include a lid that completely seals to hold in the heat. Cooking efficiency is important because of limited fuel. It is harder to heat water in cold temperatures and high elevations. This lid is also ideal for scooping snow.
winter water management gear

This method is for the Pacific Northwest

Note that the methods I’m explaining in this post are for trips in the Cascade Mountains of Washington State. This is important because you may be hiking somewhere that has colder temperatures that require different methods. Here in Washington, I’m usually hiking between 2000–8000ft and camping between 3500–7500ft. What I consider “deep cold” is typically 5º F–15º F, which is when the methods described here matter. Otherwise, expect temps to be on average between 15º–35º F here in the winter. These are thermometer temps, not wind chill.

melting snow to resupply water

In the photo above, I’m melting snow on a solidly frozen alpine lake at about 5500ft. The nighttime low was 6º F.

I don’t like being cold. I want to be warm and comfortable all the time when I’m out in winter conditions. The simple methods I’ll explain here are how I stay hydrated and comfortable in winter conditions that scare away most hikers.

How to Pack Water

Winter gear is heavy. In very cold weather, my total pack weight is between 27–30lbs. That’s with a 4-season tent, bear-resistant food container, avalanche gear, food, and water. To keep my pack weight down, I carry only enough water required to reach where ever I will be camping, which for an all-day hike is one liter or 32 oz., or sometimes one and a half liters—which admittedly is often a little less than I probably need.

When I start hiking, I typically have two Nalgene bottles and a metal flask.

  • FULL: Small Nalgene bottle (Optional, 16 fl. oz., weighs 6.2 oz.) Just enough water to drink before it freezes.
  • FULL: Thermos/metal flask (18 fl. oz., weighs 11.1 oz) I’ll drink 16oz of this and leave 2 oz as a starter fluid for melting snow.
  • EMPTY: Nalgene bottle (32 fl. oz., weighs 6.2 oz.) This is for a hot water bottle. For some trips, it is for drinking water too, if it can be consumed before freezing.

Notice that the larger Nalgene is empty. This bottle is mainly for use at camp as a hot water bottle. In theory, I could just use the smaller bottle for that purpose, but the larger bottle lasts longer during the night. In a 0º F rated sleeping bag (lower limit) the hot water bottle loses warmth about halfway through the night or 4–5 hours before becoming lukewarm. In an expedition bag (–20º F) it usually stays warm most of the night.

Most of the people who hike with me carry more than one liter of water and on most trips, it is not cold enough for their water to freeze solid. But in the colder conditions (15º F or lower), the more you carry the harder it is to keep it from freezing.

With only one liter of water, I’m very thirsty by the time I reach camp at the end of the day. (Bear in mind that there are fewer daylight hours in the winter so camp setup comes sooner unless we are hiking in the moonlight or dark.) I usually reserve a small amount (a few ounces or about 1/3 of a cup) of this water to use as starter fluid when melting snow. That is, I don’t want to just put snow in a pot and put the pot over a flame. This can damage the pot. I’ll start by heating a small amount of water and then add in the snow. I use a titanium pot with 1.5 quarts (1.4 liters) capacity. This pot includes a lid that seals the pot and holds in the heat. This lid is very efficient for scooping snow while cooking.

Use the Water in the Small Nalgene Bottle First

I start the day with a small 16 fl. oz. Nalgene bottle on my pack belt where I can access it easily while hiking. I’ll drink this first. If I don’t drink it all before lunch I risk letting it freeze. I will usually consume it all before it has a chance to freeze. The smaller bottle doesn’t pull down too hard on my pack hip-belt the way a larger bottle would. Also, if I attach it toward the back of my hip it doesn’t bounce off my leg while hiking.

Important rule: Never allow water to freeze in your water bottles. If you fill a Nalgene with water and it starts to fully freeze up before you can use it, just pour it out to maintain the use of the bottle. If water freezes a full plastic Nalgene it is unlikely you will be able to unfreeze it. The bottle just becomes a useless weight.

It is possible to unfreeze a frozen Nalgene bottle but the process consumes valuable fuel.

Be aware that a bottle full of water will freeze top-down, sealing the opening first. You can mitigate this problem by flipping the bottle upside down, but make sure the lid is tight.

Use the water in the Flask second

Once my small Nalgene is empty, I rely on the flask or double-wall vacuum insulated thermos. This will keep me hydrated the rest of the way to camp. I’ve never had ice form inside the flask in the PNW. I use a Hydro Flask Wide-Mouth Water Bottle – 18 fl. oz., a design that has been replaced with a 20 oz version. Take whatever size you require. A flask will allow you to maintain liquid all day in very cold weather, provided the liquid was very hot or oiling when you filled it.

In weather above 25º F, I usually don’t bring the flask because I don’t need it and it weighs more (10.7 ounces) than a 32 ounce Nalgene bottle (6.2 oz). Above 25º F the two Nalgene bottles are moving as I hike and usually will not fully freeze. I will not always fill the larger Nalgene completely because I only want to carry what I need. I always plan to melt snow when temperatures are below freezing. The warmer the weather, the more water I carry.

I only carry a water filter when temperatures are consistently above freezing. Water freezing inside a filtration cartridge will damage it.

In deep cold or weather below 20º F, I bring the metal flask filled with hot tea. This hot tea will cool down by the end of the day but remain fluid until I reach a camping spot. Some of that tea may end up in my diner, but that’s okay.

When I reach the camp, I melt snow to refill the flask, as well as making water for cooking a meal. I melt snow for dinner, usually starting with a Miso soup or a Pho broth drained off from cooking noodles. This soup starter meal helps me to rehydrate. Later, I’ll melt more snow to fill my empty 32 oz Nalgene with hot water. This hot water bottle goes inside my coat to keep me warm around camp or I’ll put it in my sleeping bag if I’m ready to sleep.

Winter nights are long, so I usually plan to get up and hike around the camp in the moonlight or to enjoy the stars. During this time I may heat more water, but it is rarely the case that I need another hot water bottle at night. Once a bottle is lukewarm, the sleeping bag feels quite warm for the rest of the night.

In the morning I’ll start the day with boiling water for the flask and a small Nalgene bottle. Same routine each day to resupply my water. Around camp, I’m also filling my mug with tea from my cooking pot. Although I try to get by with carrying only 1–1.5 liters while hiking, I’m always consuming more than that each day at camp. This way there is never frozen water and always enough to keep hydrated.

I mostly avoid putting boiling water in Nalgene bottles and then drinking from the bottles. I don’t know how the plastic reacts to the heat and I don’t want to consume chemicals that might be released by that process. That is, I mainly carry the large empty Nalgene bottle to fill at camp for use as a hot water bottle. Sometimes it is between my feet in the morning if I’m socializing while sitting on my closed-cell mat or just enjoying the views.

enjoying the snow
Snow camping with a hot flask of tea and a hot water bottle warming my feet.

Sometimes I break my rule about drinking from a hot water bottle. That is, I will occasionally use the small bottle as a hot water bottle too. I’ll take one of the pack straps that hold my snowshoes and use it as a necklace with the small hot water bottle attached. This allows me to put the hot water bottle under my jacket close to my upper chest for maximum warmth.

Why use Nalgene bottles?

Why not use a water bottle that weighs less? In winter it is critical that the bottle doesn’t break or leak. Wet gear, especially a wet sleeping bag, is dangerous. Nalgene bottles are simply very durable water storage containers.

Why carry a small Nalgene bottle?

Why not just take one or two large Nalgene bottles? Without a pack blatter for easy access to water, I like to attach a small Nalgene to my hip belt. The large bottles are too heavy for this method. For this method, the bottle needs to be attached close to the pack so that it is on my side and not bouncing around on the front of my thigh while I’m hiking.

Why not use two flasks instead of a Nalgene?

There are lots of ways to manage water. You could, for example, just bring two large flasks. I don’t because of the extra weight and the fact that a flask doesn’t release heat like a Nalgene. That is, a flask doesn’t work well as a hot water bottle. I use the system I have because it provides for my needs without adding unnecessary weight.

The Importance of Your Stove

Stoves are essential for maintaining the water supply. Carry the water you need, but avoid trying to carry all the water you will need for a full trip because it is too heavy and too hard to keep from freezing.

liquid fuel stove used for melting snow

No campfires: I usually camp high up on the snow in alpine zones where campfires are prohibited because organic matter (wood) is too scarce to burn. The lack of organic matter is a year-round issue. Building fires is just unnecessary trouble and we don’t need them. It is better to practice LNT and use a stove.

No water filters: Water sources such as streams and ponds are often frozen or unreachable in winter, so there is no reason to carry a water filter. Freezing weather can damage expensive water filters. I use a water filter in the shoulder seasons when I am snow camping, but only when temperatures are above freezing.

Bring both cook and no-cook food: If you’re an ultralight backpacker that cold soaks food—someone use to camping without a stove or hot food—I recommend making an exception for cold weather. Cold-soaking isn’t going to work in freezing temperatures. Always bring a reliable stove for melting snow, creating hot water bottles, and warming meals. This method is the way to stay completely warm and comfortable in cold conditions. That said, backup no-cook meals are also recommended because situations can arise that prevent setting up a stove.

Don’t lose your heat! Avoid staying out in the cold and wind unprotected while cooking. Always put on layers and wind protection first when you arrive at your camp and then start cooking. It is hard to regain body heat once you lose it. The main secret to winter comfort is to never lose your heat. If you do lose it and your stove fails, you will not have a hot water bottle and you’ll be in your sleeping bag shivering for a long time. Don’t make that mistake!

Canister fuel and liquid fuel stoves: Both canister fuel and liquid fuel stoves will work in the mild winter weather conditions found here in the Cascade Mountains, but a liquid fuel stove usually performs better in colder and windy conditions. (For more about the limitations of canister stoves see: Will a canister stove work for winter backpacking?) I use an MSR Whisperlite International stove. If you use a liquid fuel stove it is important to understand how the design works in order to position the pump correctly and make sure the coil is heated by the primer flame. Do not light a liquid fuel stove in or near a tent because the primer flame is huge and will instantly melt the tent. The windscreen is an important part of the liquid fuel system as it protects the flame ensuring efficient heat.

Windscreens are not safe on canister stoves. A canister stove with its own built-in windscreen is recommended, such as the MSR Reactor Stove System. That said, some hikers manage with simple PocketRocket stoves.

Sometimes as many as canister 3 stoves will fail. Sometimes hikers are trying to rotate and warm two canisters and that fails too. In my opinion, the best situation is multiple serviceable liquid-fuel stoves.

canister stove winter backpacking
Experienced winter backpacker using a canister stove and 3-season tent. Notice how he has dug a cooking pit. Both the tent and the pit provide wind protection for his stove.

Four winter backpacking stove tips

Because stoves are so essential to water supply, always follow these tips:

Tip 1: Have multiple fire starters. A flint is the most reliable all-weather fire starter and all you need to ignite a stove. If you decide to use a flint, practice at home first. It is not as easy as it sounds. Regardless of what type of firestarter you prefer, it is wise to carry multiple starters—flint, small lighter, and/or matches—because any one of them can fail in cold snowy conditions. Matches are most likely to fail, followed by lighters. The clear lighters allow you to see the fuel level in your lighter, but are made of cheaper materials and tend to fail a lot compared to the better Bic lighters.

Tip 2: Everyone should bring their own stove and some extra fuel in case someone’s stove fails, as often happens. Stoves are critically important and failures are not uncommon. No group should rely on just one stove.

Tip 3. Bring enough fuel. 11 fluid ounces of fuel is usually sufficient for a weekend, as is one fuel canister, but I have started to bring 20 ounces of fuel just to have extra in case someone else in the group has stove problems. It happens.

Tip 4: Always bring a stove repair kit. This applies to MSR liquid fuel stoves because these stoves can be repaired and serviced in the field. Canister stoves cannot. A stove that fails is a serious problem. At the very least, bring the tools (the wrench and cleaning needle) so you can unclog the fuel jet if necessary. Be aware that gently shaking a Whisperlite stove allows the self-clearing needle in it to clear the fuel passage. A tutorial video for servicing MSR stoves is available here: Get the service kit that is specific to your stove. Practice servicing your stove at home. I promise it is not as easy as it looks in the MSR videos. The first time you use the jet and cable tool to pull out the fuel line cable on an old stove can be painful and hard. When you can calmly service a liquid fuel stove on a cold dark winter night in the wind on a mountain top, you are a Jedi winter backpacker.

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winter backpacking