How To Purify Water In The Wilderness

Making sure that you have fresh and clean water is one of the most important skills you can have when you’re out in the wilderness. Unfortunately, even if you have a ton of water around, it isn’t necessarily safe to drink; the biggest threats to your health and future well-being are invisible to the naked eye. A microbial infection can make a problematic time being lost into something downright terrifying.

So, what can you do to be able to use the water you do find in the wilderness? Purify it! If you get lost and are out of water, or you’re going on a several day trek, knowing how to purify water is an important skill (water is heavy!). Backpackers, hikers, rock climbers…they often don’t carry all of their water with them. Instead, carry the knowledge of how to purify water—whether you’re lost or carrying several days’ worth of water isn’t feasible, weight-wise, it’s a valuable skill to have.


Step 1: Find A Water Source

Start by looking for a water source—obviously, the cleaner the better. Also, the higher up (the mountain) you are, the less likely the water is to be contaminated with bacteria, like from animal waste.


Step 2: Filter The Water

Once you’ve found a water source, you’ll need to make sure that you filter it before you engage in killing the microbes. This isn’t as important with clear, running water, but if all the hydration sources you have access to are muddy or filled with silt then you’ll want to filter it first.

There are two primary ways to make sure that you get the water filtered. The simplest way is to pass it repeatedly through a piece of tightly knit clothing. It’s not the ideal way to handle things, but it can do in a pinch and it’s a good method to know if you don’t have any other gear.

The second way is to cut the end off of a container. This container can be pretty much anything: a discarded soda can or water bottle works perfectly. This is the quickest way to make a multi-layer filtration system to get the crud out of the water.

Next, gather some rocks from half-inch to one-inch across, some gravel, and some sand. Place them in the container in that order, making sure that everything doesn’t fall out of the bottom. If you have a particularly wide gap, you may want to wrap the shirt or something around the end.

Once everything is in place, you’ll want to pour water through the contraption. It should come out much clearer than it was when it went in; if it’s still not suitable then pass it through again a few times. That should remove most of the contaminants like silt and algae.


Step 3: Kill Microbes

There are a couple of different ways to kill microbes. If you’ve thought ahead and have your gear, then you may have iodine tablets or tincture. These will kill microbes quickly and efficiently. 2% iodine tincture should be added at a rate of about two drops per gallon in clear water (and double that if the water is still murky).

You’ll need to wait half an hour after applying the tincture in order to make sure that it has time to kill off any bacteria or other nasties that are in the water.

If you don’t have iodine, you’ll need to boil the water. This is ridiculously easy if you have a pot, but if you don’t then you’ll have to get creative. In either case, keep things at a rolling boil for a couple of minutes before you let it cool to drink.

There are a few different ways to make sure that you can boil water even if you lack a heat resistant container, but the first thing you’ll need to do is build a fire and grab a few rocks which can fit into whatever container you can find.

Place some of the stones carefully around the bottom of your container, and then find a few stones which can be dropped down without disturbing the stones at the bottom. Then you’ll want to set the stones up near a fire and let them get hot. You might want to stand clear if they’re sedimentary stones, as they can crack due to moisture trapped in the pores.

After the stones get hot, use a pair of sticks (or whatever method you have handy) to maneuver the hot stones into the water. Depending on how much water you have in the container, you might be able to get things boiling with the first stone; if not, remove the stone and replace it in the fire and move on to the next one.

Keep doing this until you’ve managed to keep the water at a rolling boil for at least a full minute. Afterwards you can remove the stones and drink it, knowing that it’s free of any microbial infection.

Of course, you can avoid all of this if you take advantage of modern filtration technology and just keep a survival straw in your bag. These handy little tools are set to take over and become as common as hunting boots for those who want to make sure they’re always prepared.



While you should make sure you have at least a metal canteen in your bag, life doesn’t always afford us the luxury. This means it’s important to be able to make do while you’re in the wild, even if you have to purify water. Following the above steps can help keep you safe and alive when the situation gets grim, but there are other methods as well. Just make sure you have the process down, and you’ll be good to go.