How to Make a Water Filter in the Wild – A DIY Water Filter Guide

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The worst has happened; you’re lost on a wilderness trek and ran out of purified water. Even worse, you forgot to buy a water filter for your trip! What can you do?

All is not lost. The truth is, with a bit of ingenuity and this guide, you can make some DIY water filters that will let you stay hydrated while you figure a way back to civilization. Let’s break down how you can create these filters from scratch using common hiking or natural materials.

Why Do You Need to Filter Water in the Wild?

All of our talk about water filtration is a bit moot if you don’t know why you’re filtering water in the first place.

Basically, water in the wild is far from pure like the stuff you can get from most modern metropolitan taps. In truth, the water you find in nature is often filled with contaminants of both microscopic and visible types, even if that water may look relatively clear or pure with the naked eye. Water you scavenge from a stream or pond can have dirt or debris, which can wreak havoc on your digestive system, or bacteria and viruses that can make you sick and seriously imperil you while in the wilderness.

To drink water safely, you have to filter it. Barring that, you need to boil it. But if you can’t make a fire or otherwise boil a pot of water, you can make DIY water filters using some basic principles and tools.

These will allow you to filter your water anywhere you collect it without having purchased a dedicated filter unit beforehand.

Since humans need water every day to survive, knowing how to filter the stuff is one of the most important survival skills you can possibly learn!

A DIY Water Filter vs a Store-Bought Filter

DIY filters may differ from store-bought filters in a few key ways. There are basically two types of water filters around: physical filters and/or physical + charcoal filters. The latter are the kind most often used in store-bought filters because charcoal does a few excellent things to filtered water.

Most store-bought filters come in small, contained units that feature an apparatus with a water collection sleeve or net at the top, plus a water receptacle at the bottom. A DIY filter will follow the same general design but won’t be quite as neat and clean.

DIY Water Filter Basic Principles and Materials to Look For

The basic water filter design goes like this:

  • You have two containers, one to catch water and the other to act as a pouring cup
  • You also need an apparatus across which you can stretch a piece of cloth or fabric, like some torn shirt. This can be the top of one container if needed
  • You’ll need physical filtration elements like pebbles or charcoal
  • Once you have all the materials, you’ll pour water through the cloth stretched over the water receptacle at the bottom of the filter system
  • The water passes through the pebbles and/or charcoal, and most harmful elements are left behind in the process

Naturally, this filtration method isn’t totally foolproof and it’s not quite as good at getting rid of all bacteria as dedicated chemical filters. But it does a good job in most survival situations.

Other materials you may need include:

  • A soda bottle or any container you can cut into two halves
  • A knife to actually cut the bottle or any other improvised container – you can also use bamboo if you find some

Instead of building an apparatus, you can also just stretch your filtration net over the water receptacle, using the other half for pouring. This may be a bit easier to create with very limited materials; you just have to be careful when pouring the water so the net doesn’t fall into the purified water receptacle, ruining the batch.

Why Use Charcoal?

Charcoal is a key filtration ingredient as it’s a form of carbon that actively attracts most foreign elements like dirt, toxins, bacteria, and more. When you crush up charcoal and run water through it, the resulting water tastes better, looks purer, and is cleaner overall. It seems counterintuitive since most of us are used to thinking of charcoal as somewhat dirty or dusty. But it’s the truth! Charcoal’s bonding properties are truly astounding.

The great news about charcoal is that you can get it from any campfire you make in the wilderness. Just build a fire, let it go for a while, then crush up the charcoal and use it for your DIY water filter

What if You Can’t Build a Fire/Get Charcoal?

In the event that a fire is out of reach, you can still make a decent DIY water filter. In this case, the primary filtration agents will be the cloth you use for the main net and some pebbles or other small impediments. In both elements’ cases, they will act to separate the water from debris, pond scum, bacteria, and more.

Such a filter won’t be quite as effective as a charcoal filter, but it can still get the job done.

3 DIY Water Filters You Can Make in the Wild

Let’s get into the DIY water filter details. Here are three unique filter builds you can leverage depending on your circumstances and available tools.

Basic Freshwater Charcoal Filter

A freshwater charcoal filter is one of the best tools you can learn to make. This is because fresh water is often abundant but may be found “still”, as in ponds or lakes without very active currents. Such water is a haven for harmful bacteria. If you can ever manage it, use river water instead of pond water to avoid excess bacterial risk.

But either way, this DIY water filter will help you get at least some drinking water in short order.

Tools/Components:

  • Bottle, plastic, glass, or otherwise
  • Charcoal
  • Grass, pine needles, etc.
  • Sand, fine dirt, as dry as possible
  • Small pebbles
  • Cloth or fabric to act as a net

The great thing about this filter is that all the components are things you can reasonably expect to have during a camping or hiking trip or are stuff you can scavenge from the wild.

What you’ll want to do is start with the bottle. Use a knife, pen, or whatever other piercing tool you have to make between four and five holes in the bottle’s cap. Close the cap, then use a knife to cut the bottom of the bottle open (this may be difficult with glass bottles).

Next, stuff the fabric or cloth into the bottom of the top half of the bottle – you should place the cloth so that it presses against the bottle’s interior on the cap side of the container. The idea is that water poured through here will have to go slowly through the filtration layers and trickle out through the bottle cap’s holes.

Now put some charcoal in the bottle filter, on top of the fabric layer. Make the charcoal pieces as small as you can for the best results. After charcoal comes the sand, then the grass. The grass, in particular, should be balled up if you can to make it difficult for water to get through. This ensures that only pure water eventually makes it all the way to the bottom.

Put some pebbles inside as the last layer of the filtration system. Additionally, you can stuff any other pieces of fabric into the bottle at this point if you want to make it really filter-y.

You’re all done! The half-bottle filter is now ready to have water poured into it from the cut-open side. Water will eventually trickle through and come out through the holes in the cap. The resulting water should be much cleaner than how it was before.

Salt Water Filter

Salt water is toxic to the human body, and drinking even a little of it can start a death spiral if you’re already dehydrated. Here’s a great filter idea if you ever need to make fresh water from the biggest body of water in the world: the sea.

Tools/Components:

  • 2 bottles or other water containers this time
  • A few pebbles or rocks depending on your containers’ sizes
  • A plastic bag or similar item

This water “filter” kind of cheats as a filter at all, and it takes quite a long time to get any drinkable amount of water. It’s ideal for making water in bulk if you have large containers to spare.

In a nutshell, this system works by pouring a bunch of salt water into an initial container, then setting up your second container very closely to the first. The trick is to make the second container a little lower in physical height to the first one. This is necessary so that when the first container’s water overflows (more on that in a second), the lower container can catch the fresh water.

Run the plastic bag over the tops of both containers. Use the rocks to keep the plastic bag in place and somewhat tight over the containers’ lids.

Over time, the sun will heat the salt water and cause it to evaporate. The salt will be left behind, but the water will condense on the plastic bag. Some or most of that water will collect in the second, uncontaminated container, resulting in fresh drinking water.

As you can imagine, this takes a ton of time and may not be a viable solution if you just have a pair of water bottles. Larger containers are a bit better (think bowls or big bottles), but don’t go too large since bigger water bodies take longer to evaporate, too.

Water Extractor/Filter to Use on Plants

This last DIY water filter is a last-ditch method you can use to get a drink if you don’t see a body of water in sight… but you can find green plants. Green plants mean that there is water all around you; you just have to know how to get it!

Tools/Components:

  • Cup, bottle, bamboo container, etc.
  • Green plants (no grass if you can help it)
  • Plastic bag/sheet
  • A straw, natural or artificial

Find a spot somewhere near your campsite where there’s always tons of sunlight. Then dig a hole, preferably in a spot where it’ll get sunlight for almost the entire day. Be advised that this filtration method also takes quite a while compared to the first filter we made.

After digging the hole, stick your bottle or other container in the middle. Pick some green plants (grass can work in a pinch, but other thin plants are better) and place it around the water container, but don’t actually let the green plants go inside. Try to keep the inside clean as well, for obvious reasons.

Use a knife or another instrument to make a hole in the bottom of the container, not the top. Then stick the straw into the bottom hole. Naturally, you’ll want to keep the hole as tight as possible.

Next, cover your dirt pit with the plastic sheet. This traps heat and moisture and will progressively cause evaporation. You can use dirt or rocks to keep the plastic sheet secure – just be sure to put a rock in the middle of the sheet right above the container for maximum effect.

Over time, the evaporating effect will cause the plants’ contained water to collect on the plastic sheet, then drip into the container. You might even get some evaporated water from the soil. You can use the straw to take a drink from time to time.

Again, this isn’t a very good method for bulk water, but it can work if you have time to spare and/or are in a pinch.

Conclusion

Ultimately, DIY water filters can be lifesavers if you’re ever stranded and need to get a drink before trying to move on. However, you should still try to use a store-bought water filter whenever you can, as they tend to be more efficient and easier to use. Good luck and stay hydrated!

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