While ultralight disposable bottles reused can make great and lightweight water containers for summer backpacking, as fall begins to make its presence known with crisp nights, the occasional dusting of snow, and with backcountry trips often featuring more extended back to back bouts with wetter weather, staying warm is at the forefront of my mind.

While my efforts here focus on selecting the proper, and proper amount of, insulation across the board, sometimes nothing beats a source of warmth other than trying to trap your own. When fall truly arrives and I find myself in the backcountry during that first major cold front with multiple days of wet, rainy, or snowy weather a hot water bottle in the sleeping bag can help combat a little loss of loft in a sleeping bag, help to maintain sanity when I begin to lose the condensation battle in a tent, and perhaps even help to dry out some clothing and gear while getting a better night of sleep at the same time.

For shoulder season or winter backpacking trips, a hot water bottle at night can offer a nice mental boost.

Backpacking Bottles for Hot Water

A Nalgene Tritan bottle (more insulating) or the HDPE Nalgene option (lighter) and some extra stove fuel quickly becomes my best friend after sunset here – each bottle is capable of safely holding boiling water securely and for a less nerve-inducing experience the wide-mouth versions may be best. For a liter of water, allocating around 20 grams of extra stove fuel per bottle will usually do for most modern upright canister stoves when it’s not windy, but at home testing with the exact setup and stove / fuel choice can of course determine a more exact number. Many like to then insert the bottle into a large sock or other non-meltable clothing item to take the edge off the heat and further insulate the bottle.

For cold-footed sleepers the footbox of a sleeping bag can make for a good stash point, but I find keeping the bottle closer to my core helps more with overall warmth. While the Tritan Nalgene will hold heat longer, I find that unless I'm on a true winter backpacking trip I'm taking the HDPE Nalgene bottle since it's lighter weight, and although both types of Nalgene bottles are rated for hot water, the HDPE offers a little more peace of mind as it's rated to a higher temperature.

The benefit doesn’t stop there – one of the best parts is waking up with a liter of warm water the next morning for drinking, toothbrushing, and coffee that’s not icy cold to start with. While I don't rely on this trick for warmth on a trip of course, a hot water bottle offers a nice backup and bonus, the promise of a better night of sleep, and perhaps most importantly a psychological boost when the weather becomes challenging. When I think I might utilize the trick before a trip, I make sure to pack extra fuel and double check that I've closed that lid securely before placing it in my sleeping bag when I'm out there.

For more ways to stay warm at night, see our article: 10 Ways to Sleep Warmer on Your Next Backpacking Trip.

Editor's Note: This Trail Tip originally appeared in Issue 30 of TrailGroove Magazine. You can read the original article here.