Is It Better to Drain the Cooler or Not?

Go figure that the most contentious question of many trips is how to keep the beer cold

One of the most proud moments of my life was the discovery that we still had ice on Day 21 of a 21-day Grand Canyon trip in August. Call it a small victory, but I’ll take my successes where I can get them. I lived and breathed ice for three weeks before we left, lovingly adding a 1/2 inch of water to each cooler each day and freezing the new additions overnight into beautiful specimens of near airless magnificence. Even so, once we were on the river, ice management became a crap shoot. Every stinkin’ trip the same argument comes up: Do we drain the cooler water or leave it in? There are more passionate arguments about draining water than there are about the politics of the presidential election.

I’ve heard unwavering opinions from all: anecdotes from trips past, actual rocket scientists relaying the laws of physics, quietly confident Grand Canyon guides guaranteeing that there’s a correct process.

To drain or not to drain? That, my dear Shakespeare, is the real question.

For the answer, we turn not to an experienced outdoorsman. We hit up the bad boy of every party: physics.

No student of physics will answer a question without first setting parameters. For our purpose, here are the assumptions: The cooler is relatively efficient at doing its job, ice refills are not readily available, and responsible practices are being enforced by that one cooler cop who is always bellowing about not keeping it open for too long. We’ll also assume that it’s not the dead of winter and the ambient air is warmer than freezing.

The crux of the whole shebang is that we’re assuming the goal is to keep the cooler contents as cold as possible for as long as possible. In other words, we’re assuming you’re more interested in a cold beer than the size of the ice chunk next to it.

A Physics 101 Primer
Hot and cold always seek equilibrium. It’s not just a good idea, it’s the law of physics called thermal equilibrium. Left to their own devices (i.e. without outside influence and with enough time) a hot mass and a cold mass will always seek compromise to meet somewhere in the middle. Thermal equilibrium is achieved by heat transfer, which effectively is just the exchange of thermal energy via BTUs. We can effect the rate of heat transfer in certain situations, but in purely scientific terms, the rate is determined by the temperatures of each mass and characteristics of the medium in between them.

adventure journal photo by Eva Luedin

So how does that apply to my cooler?
Thirty-two is the magic number for the cooler conundrum. When ice comes in contact with air or a mass that’s warmer than 32º F, a heat transfer occurs. Ice will work its H2O-based ass off to cool down any non-frozen food or drink in its space. More accurately, a warm beer placed in a cooler of ice will emit heat as it chills. This heat causes the ice to melt into water until the temperatures of the remaining ice, beer, and water reach equilibrium.

Even if you were magically able to pack your cooler perfectly and with all the contents at 32º or colder, an even more critical heat transfer still exists between the air space in the cooler and the outside air temperature. No big surprise that the hotter the day, the more quickly your ice will melt.

So we know that the tipping point from ice to water and vice versa is 32º F, right? It’s also the crux of the drain-or-not-to-drain quandary because melting ice will stay precisely at its melting point (32ËšF) until the conversion from solid to liquid is complete. In plain English: as long as there is some ice left in the cooler – regardless of how much water is sloshing around – the temperature of the ice/water mixture will hold steady at 32º F.

So the ice is in a race to 32ËšF and it’s not getting any warmer until it is completely melted. If you drain the water, the ice isn’t going to get any colder. Because the water is already at 32º (and not warmer), draining it won’t slow down the rate at which the ice melts. It would only open up space for warm air to come into the cooler, which would accelerate the rate of melt for the remaining ice.

Result: In order to keep your food and drink as cold as possible for as long as possible, don’t drain the water while any ice still exists in the cooler.

Cooler Best Practices:

  • If you can, chill the entire cooler before you use it.
  • Definitely chill your food and beer before putting it in the cooler.
  • Fill ‘er up. Leave as little air space in the cooler as possible. Some recommend adding some sort of insulation to take up space.
  • Keep your cooler out of direct sunlight as much as you can. If a shade tree isn’t available, cover your cooler with wet blankets or burlap.
  • Minimize the number of times you open it and how long you keep it open.


Photos by Steve Snodgrass and Eva Luedin.

Camp Notes is a big high five to the fun of sleeping outdoors and all that comes along with it. You know, camping and stuff.



Contributing editor Brook Sutton lives in Durango, Colorado.
Showing 19 comments
  • John

    You bring up a point and then fail to account for it in your explanation… “the rate is determined by the temperatures of each mass and characteristics of the MEDIUM in between them.” The rate of heat transfer is determined by the medium doing the transfer. Water is a great conductor of heat Air, not so much. Water in a cooler not only contacts and connects the ice with the beer, it also connects the ice and beer with the outside of cooler.
    Water’s thermal conductivity is 0.6 W/(m-k). Air’s is 0.025 W/(m·K). By draining the water you basically stop the heat transfer.
    Just sayin’

    • Nathan


      • Mike

        Uhhh…Nathan, John is correct. THe specific heat capacity of a medium affects its ability to deliver and transfer heat. Put a block of ice that is at -10F into water that is 32F and that water will take the heat from the ice. IF you put it into air, the air will cool down 24x faster than 32 degree water. Hence you’ll end up with slightly warmer, but not melted ice and cold air..

        The piece of the argument that is missing is what is the temperature of the other stuff in the cooler…If it is warmer than the water, then the water can help.

        • Timmmaa

          The other piece of the argument missing is the fact that water has excellent thermal mass properties, while air has none. The thermal mass of water outweighs any and all other positives in negatives in this discussion. Leave it in there.

  • Steve

    I love these kinds of discussions on a boring winter work day. Leave the water in. Water doesn’t connect the ice to the outside of the cooler, it connects it to the inside of the cooler. Hopefully, your cooler has a nice, unbroken layer of insulation between the inside and the outside. As was pointed out, as long as there is ice present, the water will stay at 32 degrees. If you dump out the water, you’ve just thrown away a lot of mass of 32 degree heat sink that could’ve absorbed the heat. Now, instead of a lot of mass absorbing a little heat you have a lot less mass of ice abosrbing the heat and melting. Then you throw that away and drop the mass again. It’s a death spiral. The total mass of the system is probably more important than the specific heat capacity.
    Of course none of this matters if you leave the cooler in the sun and your kids open it 50 times a day.

  • jon Canuck

    Drink the beer during the first couple of days — go on a beer-fast after that. Put left-over ice on guy’s nipples. This advice from the Great White North.

    • JC

      Beer fast? Jesus man, that is some harsh austerity. Not sure how to respond to the nipple comment.

      If you are doing it right on the Grand, you’ll have ice in your coolers and a dedicated non-meat cooler from which you can draw ice for cocktails.

  • 3guys

    The real Question. In the cold outdoors, is it best to get naked in your 0 degree REI bag, or keep every stitch of clothing on to keep warmest?

    • John Tannock

      Depends who’s in the bag with you!!!

  • hockdub

    While this discussion touches on keeping the temperature regulated, there’s another side to the coin – keeping things dry in a cooler full of water can be difficult, however – containers help mitigate this issue. I may be breaking the rules, but most of the time I try and use cooler water for dousing fires, cleaning dishes, or hydrating the dog… this helps conserve the other clean water that was brought along on the trip.

  • Robi

    Who uses a cooler for beers in the Canyon?

  • Mowgli

    Well, I have pondered this question plenty. So when my new Canyon Sailor 105 showed up, I decided to do a simple experiment. For weeks ahead of time I filled 2 quart plastic bottles with water and placed them in the freezer until I had enough to pack said cooler. 1/2 marked red and 1/2 marked blue. I put all the frozen bottles in the cooler and put the cooler outside where it would remain in the shade but still exposed to the outside temps which were about 85/90 degrees during the day and about 65/70 at night. I placed a wet towel over the cooler and kept it wet as best I could. Each evening, as quickly as I could, I popped the cooler open and removed the red bottles quickly shutting the cooler with the remaining blue bottles inside. I poured the melted water out of each bottle and put them all back into the cooler. The blue bottles never got touched. The result…. The blue bottles (undrained and not taken out of the cooler) were iceless in 5 days. The ice in the red bottles (taken out of the cooler and drained daily)lasted until day 8.

  • Ken

    Just buy a Yeti.

    Then you only have to worry about your $500 cooler running off the moment you take a little snooze.

    The only timing you’ll have to worry about is how long it will be before the sun melts your ice – and the beer will likely be drunk before that.

  • Greg D

    This whole argument seems to ignore the water sloshing equation.
    If the cooler is simply sitting the thermal equations may work. Question is, does water erosion speed the melting of the ice? Air will cause no erosion melting correct?

  • Ted

    If the cooler is sitting in one place, leave it in. If you have to carry it any distance, dump it out!

  • Steve

    There is an aspect to this discussion that needs attention and has had none. That is, that I like my beer to be served at less than 32F. I live in the tropics and if I’m served a beer from an icebox containing ice AND water I’m not happy. I will know immediately. So to keep me and the fellow patrons of my local bar happy, a drain is fitted at the base of the iceboxes. Longevity of the ice is of little consequence to me and my icy cold lager.

    • Mick

      You sir need dry ice for the cooler! And I like this idea! But, I’m thinkin’ I’d wind up with a buncha exploded beers.

  • Casey Halstead

    The Grand Canyon is hands down the ultimate test of ice in a cooler. I am certain that all the Grand canyon companies are not wrong. Drain the water!

    • Mick

      I think I may have gleaned some real world experience type of wisdom here.
      Thanks Casey!
      Is that what they instruct?
      We can apply a ton of science to the problem but sometimes the math just isn’t complete.
      It’s like going to mechanical school/college and graduating with honors, but when you get out there actually start wrenching on stuff, you realize you don’t know squat!

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