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Using Hot Water Bottles In Your Sleeping Bag to Warm You Up

Staying warm in a sleeping bag is more of an art than a science. Optimizing gear will take you a long way, but it’s the little tricks that get you to your goal.

Of course, you should pay attention to your sleeping bags temperature rating, decide between down and synthetic insulation, use a sleeping pad, bag liner, etc. But that’s only brushing the surface when it comes to staying warm.

Here’s a simple trick to guarantee a warm night’s sleep. Tossing a hot water bottle in your sleeping bag will warm it up in no time.

Should You Put a Hot Water Bottle in Your Sleeping Bag?

Yes, you should definitely put a hot water bottle in your sleeping bag overnight. It will warm up your bag and guarantee your water bottle doesn’t freeze throughout the night.

Artificial heat can be a serious game-changer in the cold. It warms up your bag before you get in and keeps you warm throughout the beginning of the night.

Just remember that a hot water bottle isn’t a magic pill. You still need to pay attention to your sleeping bags temperature rating, use a sleeping pad, bag liner and wear insulated clothing.

Here’s a guide on layering clothing in a sleeping bag for warmth.

What Kind of Bottle Should I Use?

Personally, I always just fill up the same old Nalgene Water Bottle (On Amazon) that I’ve been using for years. Nalgene bottles are crush-proof and have secure rims so they rarely leak.

The only downside is there’s no insulation between the bottle and your legs. I either wait 20-30 minutes for the bag to warm up and bottle to cool or wrap it in a sock which adds a little insulation.

Just make sure the rim is wide so it’s easy to pour the boiling water and the rim is clean and dry. If ice gets into the rim of your water bottle you won’t get a good seal(nobody wants wet feet). You should then put the bottle in some type of insulation cozy to keep it warm longer.

You Can Even Use a Hydration Bladder

You can save a little weight in your pack by choosing a hydration bladder over a standard water bottle. A hydration bladder (Camelbak, Platypus, Etc) is going to form to your body and be wat more comfortable.

Just keep in mind that filling up a hydration bladder with boiling water is a challenge in thick winter gloves. Plus a hydration bladder is much more likely to fail than a standard Nalgene.

You Don’t Want The Bottle to Leak

Don’t cheap out when choosing a water bottle. Skip the cheap 1 dollar water bottle you find at Walmart. The cap needs to have a perfect seal so water won’t leak in your bag.

Make sure the bottle can actually withstand boiling hot water so it doesn’t melt getting water all over the place. You can’t just use any old water bottle it needs to be hot water safe. Most (but not all) bottles that are labeled dishwasher friendly can withstand boiling water.

Watch Out For Bare Skin

Be careful when pouring boiling water into your bottle, and I’m not talking about the occasional spill. The water bottle is going to be seriously hot to the touch.

If you’re using a metal water bottle it’s going to be extremely hot so wrap the bottle in a sock so it won’t touch your skin. The insulating sleeve will both protect you and keep the bottle warm longer.

Don’t Sleep Naked

Ever have somebody tell you that it’s better to sleep naked in a sleeping bag? Whoever started that rumor probably just wanted to see somebody get naked. Sleeping naked will both make you colder and speed up your bags degradation.

This is why you shouldn’t sleep naked in a sleeping bag.

Definitely wear longjohns, sweatpants, pajamas, etc to bed. Layering will both keep you warmer and protect you from the hot water bottle.