How to Make A Water Filter: Step By Step Guides

My two decades of outdoor exploration have taught me one vital survival skill: creating my own water filter. And I am here today to share this knowledge with you. So, let’s dive into the world of DIY water filtration.

Without water, survival is measured in days, not weeks. And dirty water (or salt water that I talked about here) is worse than no water at all, because it trades dehydration for something potentially far more dangerous: waterborne illness.

In this guide, I’ll walk you through four different methods, from basic sand filtration to a technique backed by MIT research. I’ll also be straight with you about what these filters can and can’t do, because that honesty might matter more than anything else here.

So let’s get started and learn how to make a water filter – a few methods that are easy to learn.

Related Post: How to Purify Water with Bleach

Before You Start: What You’ll Need

• A container to collect the unfiltered water
• A second container to gather water filter materials
• A third container to store the filtered water
• The will to create your water filter

That’s the universal setup. What goes inside the filter depends on which method you choose, and I’ll cover that in each section below.

1. The 3-Step Sand Filtration Process

The 3-Step Sand Filtration Process is a straightforward method for filtering water that employs modest natural resources to transform murky water into a potable lifesaver.

Here is what you need to know to filter water using the 3-step sand filtration process:

Step 1: Container Craft

A sturdy container forms the cornerstone of your makeshift filter. A bark from a tree works wonders in a natural environment where plastic containers are a luxury.

Mold it into a cone, sealing a small hole at the bottom for the filtered water to trickle into your collection vessel.

To prevent your container from falling apart, secure it with a string or any other available material.

Ensure the smaller end of your cone faces downward, adopting a funnel-like structure.

Step 2: Gathering Filter Materials

Next, we need to fill our cone with the filtering components:

• Pebbles and sand
• Non-toxic grass (to form a mesh)
• If available, some cotton material (to enhance the mesh)

Begin by layering the mesh and pebbles at the bottom of your cone. I like to add a layer of gravel for an extra layer of filtration and to prevent the various materials from jumbling up.

Then, it’s time for our star player – sand. Grab a handful of sand and layer it atop the other materials until you have filled a decent part of the cone.

Step 3: The Filtration Finale

In your first container, collect some water from your source. Steadily pour this water into your cone, and watch as it trickles through your layered filter materials, emerging as clean water into your receiving can.

Pat yourself on the back because you’ve just successfully filtered your water!

Should the first run leave you with less than crystal-clear water, don’t sweat it. Remember, repetition is the mother of all learning. Go through the steps again until the outcome meets your satisfaction.

A hot tip from my many expeditions – switching out the filter material regularly can significantly enhance the filtration process.

And, to make it even safer to drink, I recommend boiling it afterwards as bacteria and other microorganisms can still be present after filtering water this way.

2. How to: The 3-Step Charcoal Process

Let’s face it. The water you’ll stumble upon in the wilderness is usually muddy, dirty, and rather unappetizing.

The sand process above handles that first layer of grime well, but if you suspect more dangerous elements are present, like Giardia lamblia, a common protozoan parasite that causes waterborne disease, or any other microorganisms (and you should always assume they’re present), you need to take extra precautions.

Never rely on sand filtration alone for safety. It doesn’t kill bacteria or parasites. Boiling does. But when boiling isn’t possible, charcoal is the most valuable additional step you can take, and it can be applied either directly or after running the water through the sand process first.

The best part is that charcoal is relatively easy to produce if you don’t have it on hand. Here’s how:

1. Make a Fire: Simply let the woods burn into a hot bed of coals. Once you’ve got that going, cover the coals with dirt and let them cool. And voila! You have your charcoal.
2. Setup Filtration: Next, get your cone or filtration container ready. Add a layer of charcoal balls, top it with some sand, and leave space to pour in your water.
3. Collect Water: Now comes the satisfying part. Collect the water as it flows out, having been purified by the filter materials.

Even with charcoal in the mix, you’re still working with a filtration system, not a purification one. Charcoal removes sediment, some impurities, and odors, but it does not reliably eliminate viruses or all bacteria.

Boil the output whenever you have any way to do so.

Charcoal vs. Activated Charcoal: Which Is Better for Filtering Water?

While regular charcoal does a solid job, activated charcoal is the stronger choice. If you’ve got some in your backpack before heading out, great. If not, regular campfire charcoal works perfectly fine.

After all, regular charcoal has been a stalwart in water purification for centuries, even being used in controlling odor from putrefying fishes between the fourteenth and seventeenth centuries.

Bottom line: activated charcoal should always be your top choice, but if that is not available, any type of charcoal is acceptable. Just make your own and filter water with it.

3. Filtering Water Using the 3-Step Agave and Cork Processes

If you’re in a region where agave grows, think deserts and dry climates, the agave stalk makes a surprisingly effective natural filtration tube. Cut out a section, make it hollow, fill it with charcoal and sand, pour water in, and collect what comes out.

Here’s the full step-by-step:

Step 1:

Cut out a section of an agave stalk and split it down the middle in order to make it hollow.

This should go all the way down, but you should leave a section of about six inches unhallowed.

The plant stalk grows up to about twenty five feet, but all you need is a six-foot section for your experiment.

Step 2:

Make a fire, and fill up a section of about four feet of the stalk with your layer of charcoal, and about one foot with sand, or could just leave the top two feet free to hold your water that is to be filtered.

Then tie up the stalk, realigning the hallowed sides back together in order to hold your charcoal in place.

Step 3:

Pour the water to be filtered into your agave stalk, and watch your DIY water filter do its job as the water seeps through the charcoal and permeates into your collection container.

Cork Process:

This is the method I find most fascinating, because it has serious science behind it. What people in survival circles have long called the “cork process” is a primitive version of xylem filtration, something MIT researchers have studied in depth and published on.

The field version works like this:

Step 1:

Get a hose or an empty plastic bottle and cut off the broader end of the bottle.

Step 2:

Cut the branch of a tree preferably a white pine.

Reduce the branch to the size of cork. Peel off the bark and insert the cork into one end of the hose, or the smaller end of the plastic bottle. Tightly fasten the hose unto the cork and pour your water into the filtration tool.

Step 3:

Collect the filtered water as they seep out through pores of the cork and begin to use it.

4. The Plastic Bottle Filter

This is probably the most practical method in this entire article, and the one I reach for first when I have the materials available. Most people in an emergency situation are likely to have a plastic bottle nearby, which makes this method the easiest.

What you need: an empty plastic bottle (one liter or larger works best, though a two-liter is ideal), fine sand, small pebbles or gravel, grass or cloth, and charcoal if you have it from the method above.

Step 1: Cut off the bottom of the bottle. This open end becomes the top of your filter, where you’ll pour the dirty water in.

Step 2: Invert the bottle so the cap end points downward. Punch a small hole in the cap, or simply unscrew it slightly to allow filtered water to drip through into your collection container.

Step 3: Layer your materials from the cap end upward: start with grass or cloth at the cap end to act as a natural strainer, then add two to three inches of charcoal, two to three inches of fine sand on top of that, and finally two to three inches of small pebbles or gravel at the top.

Step 4: Hold or prop the bottle over your collection container, pour the dirty water in through the open bottom end, and let gravity do the work.

The order of layers matters here. The pebbles and gravel catch the largest debris first, the sand filters out smaller particles, and the charcoal, which you learned about in Method 2, handles impurities and odors. If the output still looks murky, run it through again.

And as with every method in this guide: filter, then boil.

When These Methods Won’t Be Enough

There’s one scenario I want to be straight with you about. If the water source you’re working with is chemically contaminated, no DIY filter in this article will make it safe to drink.

Chemical pollutants like heavy metals, pesticides, arsenic, or industrial runoff are not removed by sand, charcoal, sapwood, or any combination of them. They’re invisible, they have no smell, and boiling won’t help either.

If you’re near heavy industry, agricultural land with fertilizer runoff, or anywhere you have reason to suspect chemical contamination, these methods are not sufficient on their own.

In a true survival situation, you may have no choice but to use them anyway, but going in with that knowledge lets you make a more informed decision. Whenever possible, rainwater or dew collected from non-poisonous plants is a cleaner starting point than chemically suspect surface water.

Wrapping up

There you have it! With a little bit of creativity and a thirst for adventure, water filtration in the wilderness can become second nature.

So next time you’re out there, remember that nature provides, and the keys to survival are all around you. Happy adventuring, folks!