I read on forum, that drinking (very) cold water is not good, because body needs more energy to heat cold water and warm you up.

I want to know at what temperatures should I heat water, where would you say it is the limit?

I will be hiking in areas a little above freezing point, so I guess I need stove(extra weight) or put the bottles in my sleeping bag each night. Because water filter could freeze I will use tablets and stove for heating.

  • 1
    If there's a risk of freezing, you need to bring the stove (or have some way of heating) anyway, because you can't drink ice.
    – PMF
    Sep 18, 2022 at 20:11
  • Highly subjective as it entirely depends on the situation - if you are out for an hour or two and well protected from the cold, then drinking ice-cold water won't be a problem, but overnight? multiday? outside temps? What protection do you have?
    – bob1
    Sep 18, 2022 at 20:51
  • It depends on your current body temperature, how much you drink, and how much you need the water. If you have been exerting, you'll probably have excess body temperature anyway. Sep 18, 2022 at 22:09
  • The hikes are usually multi day, that one will be up till 5 days, 10-12 hours per day of activity. Temp range: -2C(28.4 F) till 12 C(53 F). There are some huts on the way, but I will have to spend some nights at biouvac or tent. I have good clothing and sleeping bags, but since i drink a lot of water that is an important thing in such low temperatures. There wont be any ice, but the water will be very cold.
    – Alex J.
    Sep 19, 2022 at 10:28
  • I've drunk glacier melt often enough. The temperature of that water is 0-3°C. It feels nice when you're really tired. But not that good, because it is actually cold all around. More importantly, it'll quickly give you a sore throat. At high altitude and low temperatures, that can lead to worse things. Better avoid it except for the novelty charm. There's also a chance it could be contaminated on busy routes.
    – ahron
    Sep 22, 2022 at 17:16

1 Answer 1


As others commented, it depends. But unless you are at camp 4 on Everest or in a similar extreme situation, it won't actually matter much.

If you do the math or let online calculators do it for you (i.e. here) on how much energy it takes to warm water, it's not actually that much. If you go to the extreme and say you down 4l of 1°C water and need to heat it to 36°C body temp, it takes about 140kCal or about half a chocolate bar. Of course, the body will burn a bit more energy to heat up the water but keep in mind, this is an extreme example.

Personal experience: 10 day hike, 20km a day, nights in a tent, temperature between -10°C at night and about 5°C during the day. Had water in a pack in my bag a quite a bit of the tube stuck outside so I was basically always drinking ice cold water. Of course the hot coffee in the morning was more enjoyable than always drinking ice cold water. But I never once felt cold because of cold water or burning more calories even though I severely underestimated how much food I needed (basically had a 800-1000kCal deficit for 10 days). Quite the opposite actualy, as soon as you get moving, you get quite hot and the body will have temperature to spare to heat the water.

So, I'd say no, not dangerous if you otherwise keep well fed, rested, dry and warm (clothes, sleeping bag).

  • +1 You might want to add that at the temperatures the OP is anticipating, keeping the water bottles inside the tent, not necessarily inside the sleeping bag, should be adequate to keep the water from freezing.
    – ab2
    Sep 21, 2022 at 23:50

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