A Survival Water Filter





Introduction: A Survival Water Filter

In the world we live in, you never know what is coming next. Fires, hurricanes, and other natural disasters can lead to apocalypse-like situations. That is why you should always be prepared to be able to survive in many conditions. One key factor to survival in all situations, is getting clean water for drinking. In this Instructable I will show you how to build a filter for water purification, using only materials found in the wilderness (from scratch), with the exception of cloth. I will also show you where to get water in the wilderness and how to finally boil your water for purification in the wilderness.

So let's get started!

Step 1: Gather Your Materials

For this Instructable you will only need to use one tool - A knife

Here is the list of the materials we will be using:

-Birch Bark

-A Small Live Branch or Small Live Plant




-An Article of Clothing (Preferably a Bandana)

The first thing we are going to need for the filter is the birch bark. We will use this bark to hold the filter together in a cone shape. In order to shape this bark correctly, you have to cut the bark in a half circle with a diameter of roughly one foot. Using this shape you can roll the bark into a cone. Of course, this is the natural materials only version of this filter. Instead of using Bark to make the filter shape you could use the top of a water bottle that is cut in half

The second item is a small live branch. Normally I wouldn't cut live branch, because I don't want to harm living things, but this is a survival situation. We need to use the live branch to tie the cone shape together. Use branch or plant that is roughly a foot long and as thin as paracord.

The third, and most important item, is the charcoal. Make sure the charcoal that you use is bought from the store, otherwise you could get ash in your water and it could be poisonous.

The next materials include stones and gravel. If you are in an area that does not have sand, then do not waste your time looking for it because it is not the most important part of the filter. You only need about a handful off each of these materials.

The last material is a type of cloth. Although it is not found in the wild, cloth may be the easiest item to retrieve on this list, considering that most people wear clothing. A bandana works best for this part of the filter. If you do not have a bandana

Step 2: Build the Filter

This filter is actually very simple and easy to build. The difficult part is boiling the water you filter.

The first thing that you should do is roll the bark into a cone and use your knife to poke a hole through the overlapping part.(image 1)

String the leaf or branch that you picked earlier through the hole and tie off the end using a square knot. If you do not know how to tie a square knot, use the directions from my other instructable on how to do so.(image 2)

Now, take your pieces of charcoal and put them in the center of the piece of cloth you have(image 3). Now bring all the corners of the cloth together so the charcoal sits in the bottom(image 4). Now, covering the charcoal, use your hand to smash it into a powder(image 5). Put the part with charcoal into the cone and spread out the corners so you can see the charcoal(image 6).

Pile on the gravel and then the rocks and your filter is set to go.(images 7&8)

Step 3: Find Water

I will show five good ways to find water in the wild:

  1. Standing Water
  2. Running Water
  3. Using a Solar Still
  4. Plant Perspiration
  5. Cutting vines

1. Lakes, and Ponds (image 1). Standing water is very easy to extract water from. All you have to do is scoop up the water, pour it through a filter, and boil it. Try to use larger sources of standing water because then there is a lower sediment to water ratio. Always scoop the water from the top surface of the water.

2. Rivers, Creeks, and Streams (image 2). Running water is very easy to extract water from because it is moving and you can fill up a container without any effort. The only problem with running water is that it can be in a very small stream and hard to fill a container with. Remember to filter and boil this water.

3. Using A Solar Still (images 3-5). A solar still is a very neat way to get water that you can build pretty easily. The only problem is that you need a couple of items that don’t belong in nature. They include a plastic sheet (preferably clear) and a container for water (I use a cup). A solar still is basically a tiny well with some vegetation inside it. The well is covered with a plastic sheet which all the moisture is brought up to. In the center of the sheet is some type of weight which the water runs down off into the cup.

The first step is to dig a hole in an area that gets a lot of sun (image 3). Then find some small plants that are alive and very green. Rip these plants out of the ground and scatter them throughout the hole. Now take your container and place it in the center of the hole (image 4). Take the plastic sheet and stretch it over the hole. Using sticks or big rocks, stake the sheet down. Finally put either a log or a rock in the center of the plastic sheet and wait for a few hours (image 5). The water from a solar still doesn’t need to be filtered but it does need to be boiled.

4.Plant Perspiration (images 6-8). Plant perspiration isn’t the real name of this method, thats just what I call it. This method, like the solar still, also uses one item that can’t be found in nature, a plastic bag. All you need to do is put the bag over a branch of the plant. The plant will release moisture and it will get trapped in the bag. This method works well but you need to wait several hours until you have enough water. You do not need to filter this water but you do need to boil it.

5. Cutting Vines (images 9&10). This is the most unreliable method of them all, but it does work under certain conditions. The only problem with this method is that large live vines are hard to find and sometimes they are not alive. You also need patience because it takes a while for the water to drip out of the vine.

Step 4: Boil the Water for Purification

Boiling water in the wild is no easy task and It can be very frustrating. I will show you one way to boil water will only natural items and I will give you suggestions on other ways of doing it.

The way I will show you is boiling water in a hole in the ground. You will need to be in an area where clay is under the soil. We will use the clay to line the hole in the ground so that no water leaks into the earth. This is pretty simple, dig two holes, one for boiling and one to get clay. Take the clay and add a little bit of water to it so you can apply it to the hole. Seal off all the dirt. Now you can pour water into it and get your fire going along side it. You will need to find dry rocks to do this (wet ones will explode). Put a few rocks in the fire and once they have been in the fire for a while, you can put them into your water using another two sticks as tongs. You know its boiling when its bubbling.

other ways to boil include:

-In metal cookware over a fire

-In a water bottle in the fire

-In a live leaf over the fire

-In a wooden bowl you whitled

Step 5: The End

Now you know how to put together a water filter in the wild. The gray tint in the cleaned water is due to the charcoal, but as long as you boil the water it should be o.k. to drink.

This method for water purification is for SURVIVAL CONDITIONS ONLY, and it is not the best method of purifying water if you are near civilization. I am not responsible for any injuries or medical incidents related to this instructable.



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    47 Discussions

    it works very well I took it when I went camping except my water was a little weird tasting but that could be because of the wood

    cool info. on how to make a water filter


    2 years ago

    could just carry some water purifying tablets?...don't know if they would kill more bugs

    1 reply

    the tablets only kill germs, but wont get rid dirt and bugs

    Being as nice as I can, this could get someone hurt, sick or killed. First that black stuff he gathered was not charcoal, or at least very little charcoal. A lot more lye than charcoal. That's what is used to make soap. Charcoal is made by heating wood in an oxygen free container. The wood is put into a metal container with a tight lid, but not airtight. Then a very hot fire is built around the metal container and all the gases are driven off the wood. Going to be hard to make charcoal in an emergency.

    In the US birch is only found in the North and mostly in the NE. In the south I don't know of a tree with bark that could be used for a funnel.

    The water is probably safer before it was poured through the lye coals and dirty handkerchief. I would drink the water as is, before I would use this method. But I would only drink it if in danger of becoming seriously dehydrated. Certainly not as an experiment.

    Boiling water in a clay pit? How many areas don't have clay? I also doubt you could get all the water in a clay pit hot enough to boil for 10 minutes.

    So no clay, no charcoal, no birch and if I forgot the water, what are the chances I can start a fire. The blackness in the water was indeed from the ash...I don't know if you can see the lye in the water.

    2 replies

    There are literally millions of birch trees here in Alaska. Most of the forests in the southcentral area are birch (lots of white birch, with many silver birch as well), black spruce, and cottonwood. We also have lots of alders and willows. I use downed white birch for many projects. Fortunately, I have never been in a true emergency situation in which I have felt justified to cut into a live tree. When the road crews go through clearing out roadsides, park trails, and powerline trails, we are often given permission to use those trees before or right after they are cut.

    thanks for the info on charcoal, I will edit that part as soon as I can. And lots of other tree bark can make a funnel shape. And I know that clay cannot be found everywhere, that is why I added the other methods of boiling water

    If only I could guarantee that I'd get stranded somewhere that birch trees grow!

    That rules out Asia, Australia, Africa and South America, and much of the Middle East.

    Not to mention that I would naturally have a knife on me and some way to make a fire to make charcoal and boil the water, and of course, a container for boiling the water!

    2 replies

    When was the last time you were in any of those places? If you answer never, then chances are you will not have to concern yourself over being stranded there.

    Why wouldn't you have a knife on you? At the very least, why wouldn't you have an emergency kit in your vehicle just in case you did get stranded somewhere that didn't have cell service? Even if you just keep a stainless steel coffee mug, 32 oz plastic bottle of water, a couple power bars, a box cutter, a lighter, a road flare, a flashlight, a tarp/drop cloth, a blanket, an extra t-shirt, and a roll of duct tape in a small backpack in the trunk of your car then you'd have everything you needed. You'd have an initial source of water and food, a means of boiling water in the coffee mug, once emptied the plastic bottle can store the freshly boiled water while you boil more, a cutting tool, a way to make fire, a signal device/back-up fire starter, a cover element, a cotton filter/bandage, cordage/tape, and a container to carry it all.

    I carry almost all of that stuff on a daily basis, minus the tarp, blanket, and road flare, into work with me in my laptop bag and pockets.

    I carry all of those plus a couple of space blankets (they take up almost no space and are efficient heat preservers), a couple of large plastic contractor bags (useful as emergency bivy sacks or sleeping bags, or for ponchos in heavy rain or snow), and lastly, my fire starter kit - magnesium striker (file off shavings with my pocket knife, then strike sparks with the dull edge of said knife) and a drug store plastic pill bottle with cotton balls that have been rubbed in Vaseline. I also have heavy duty aluminum foil to facilitate clean-up from the fire. Don't forget some toilet paper or paper towels!

    For one, filter-quality charcoal can incredibly hard to make. Wood ash contains lye, which can really put a hamper on your water drinking. Secondly, this filter does nothing for biological contaminates and a lot of chemical ones. Your best bet is always boiling.

    9 replies

    actually, unless the charcoal is broken up to pea size or smaller, it's not going to be very effective for filtering out chems either. i hate to say it, but the volume of charcoal in this filter isn't very high, and the rocks are doing nothing but wasting space. it should just be 1/4 sand and 3/4 charcoal and really, the basket should be larger. it's a nice idea....it just needs refining.

    One can usually buy small or large quantities of sand at a pet store or garden store.

    If you're getting water from a lake or river there is usually sand somewhere around it. Other sources of water don't need the filter anyway. I agree with the other comments, rocks are completely useless, should be more charcoal. I'd like to do some research into the safety/effectiveness of using charcoal straight from a fire for water filtration. If it helps great, but I would probably just boil my water and live with eating a bit of sediment.

    Even still, there are a lot of chemicals you just won't get out with this method of filtration, no matter how you work it. That's still not addressing all the parasites and other nasty organisms that this kind of filter won't do anything about. You can pass the same water through a filter the size of a bath tub and still wind up with giardia.

    Your best bet is to boil it, or set it out in the sun for a few hours.

    To be fair, the author did say to crush the charcoal into powder. Unfortunately it's not clearly shown in the pictures, I had to read through twice to find that bit.

    Smaller than pea size, I'd say, just judging by the charcoal I use in my fish tank filters. The sand is just to get detritus out, like hair and crap. Charcoal filters are still pretty ineffective without some serious engineering. Even your Brita water filter is really only there to take chlorine taste out of water, but it even says it's not a chemical or biological filter. Charcoal only affects taste, not quality.

    Not to mention... don't you get stomach cancer from eating coal? That's at least the reason why pizza ovens using coal have been outlawed in my country.