Nothing quite beats a refreshing ice cold drink after a few miles hiking in the summer heat!
If you’re wondering how to keep drinks cold in a backpack, or asking yourself if it’s even possible, read on for some top tips on how to keep your drinks cooler for longer while you’re out on the trail.
It’s important to drink regularly when you’re out hiking in the heat. While you will naturally become thirsty as your body seeks to replace moisture lost through exertion and to cool down, it can be pretty unpleasant drinking warm water on the trail.
You will probably find that keeping your drinks cooler in your backpack will encourage you to drink more regularly and in consistent quantities, which in turn means you’re less likely to dehydrate.
To stand a chance at keeping your drinks cool, or at least not too unpleasantly warm, it helps to understand why hot drinks cool down and cold drinks warm up.
Basically, both drinks adjust to the ambient temperature. A cold drink will absorb energy from its environment, while a hot drink loses it to its environment.
In a closed system, the second law of thermodynamics ensures that a thermal equilibrium is reached between an object and its surroundings. Under normal conditions heat flows naturally from an object at a higher temperature to another at a lower temperature.
So, basically speaking if we want our cold drink to stay cold, we’re going to need to minimize the difference between its temperature and its surroundings. This will limit the amount of heat that will be transferred to our drinks. Science lesson over, let’s put this into practice!
As with many things in life, preparation is key. Start by getting your drinks as cold as possible. If you’re setting off from home or somewhere with access to a freezer, then put your drinks in to freeze. Remember water expands as it freezes so don’t overfill!
If you’re in a hotel or hostel, your best bet is probably going to be to purchase your drinks from a nearby store as you set off. If possible select the coldest at the back of the cooler.
If possible grab an ice pack or two and stick them in to freeze. Stores may have disposable thin plastic ice packs ready to go in the chiller cabinet.
Once you’ve got the coldest drinks you can get your hands on, the challenge is to keep them that way, for the next few hours at least. As you can’t take the fridge with you, you’re going to have to find a way to keep the drinks surroundings, i.e. your backpack, as cool or cooler than the drinks to prevent them heating up.
Insulation is the key here to minimize any difference in temperature. Put your cold drinks with an ice pack, if possible, in a plastic bag. Depending on your circumstances an insulated thermo bag would be ideal, however, if you don’t have one to hand, use any plastic bag to protect the rest of your gear from any water.
Wrap this inside your sleeping bag, spare layer or any other insulating gear you’re taking with you and place it at the bottom of your backpack. The more insulated they are, the longer your drinks should stay cooler. Just be sure to not get anything wet if you need to wear it or sleep in it at night!
Freeze Some Water
I personally prefer to freeze a plastic water bottle or two overnight, and then pack them away, wrapped to keep them as cool as possible for longer. I’ll ensure the water in my hydration bladder is cold, see below, when I start out so I have cold water for the first hour or two.
This gives me easy access to cold water early on my hike, while keeping the interior of my backpack a little cooler too. I then replenish my bladder with the water from the bottles when it melts. Remember they were frozen, so they will be colder for much longer.
When the day is at its hottest, your drinks should remain cool in your backpack. As you consume them and with the passage of time, they will inevitably heat up, however, they will be much more pleasant to consume than warm, tepid water.
What About my Hydration Bladder?
If you prefer to use your hydration bladder in hot weather, I would recommend putting some ice directly into the bladder and insulating it well in the center of your pack.
Bear in mind you won’t be able to freeze it as you’ll risk splitting the tubes. Also any water in the tube is going to warm up when you’re out, so either take large gulps or remember to drink more regularly to avoid it becoming too unpleasant.
Cold Drink Cheats
Make the most of your surroundings. If your hike passes any creeks plan to stop off to eat nearby. On arrival place any warm drinks in the cool waters and let them cool for at least 30 minutes.
By the time you’re good to go, they should be cool for later on. Wrap them in a wet item, then a plastic bag and insulate inside your backpack. If it’s really hot you’ll want to take a dip yourself or wet your clothing and headgear.
If you have a Lifestraw or similar, you could drink the cold water directly from the creek itself. If you know that there will definitely be water in the creek at that time of year, then this could allow you to reduce your pack weight by carrying less water. Note: Always be sure to check in advance if it’s OK to drink the water, even with a filter.
If your hike itinerary passes near any small towns or villages, check ahead to see if there are any nearby convenience stores that wouldn’t require much of a diversion. This can also help to keep your pack weight down, as you won’t need to pack as much water at the start. Carrying less weight, you’ll exert yourself less and perspire less.
One product I’ve used non-stop over summer is my Aquatix stainless steel sports water bottle, pictured below. If you’re looking for a hassle free way to grab a cold drink and head out the door, this takes some beating.
I use it for the first few hours of my day hikes and it’s really handy for keeping a cool drink to hand, without opening and warming up the rest of my drinks.
It has a lock feature and a flip top so you don’t have to worry about soaking the rest of your gear. It’s also excellent for keeping your drinks warm in winter, so you can use it year round. Check it out here.
How to keep drinks cold in a backpack – start with ice cold water and use plenty of insulation. If possible make use of any possible resupply points on the go and invest in a specialist insulated sports water bottle, you can also use it in winter to keep your drinks warm.
Remember too that freezing good old fashioned plastic bottles overnight before your hike, can help to keep your water colder for longer, but on a really hot day, this will have limited use.
If you’re heading out far in the heat, don’t forget to keep drinking water regularly. Even if you don’t succeed in keeping your water as cool as you’d like for one reason or another, remember, drinking warm water will still keep you hydrated.
So, whether it’s refreshingly cold or bordering on unpleasantly warm, keep drinking and stay hydrated!