Water is (literally) the source of life. Ironically, it can also be the source of sickness or even death. Well, not the water itself, but any pollutants that may be in it. To keep yourself safe from an upset stomach (or even worse), you will need to filter any water you can see is not clear. Learning how to make your own DIY water filter can be a life skill.
Reasons for filtering water
If you drink polluted water, it can affect your digestive system and upset your stomach. At the best, this will lead to bad diarrhea and vomiting. At the worst, you could develop something like dysentery, which needs to be treated quite quickly. The problem with any of these conditions is that you can become dehydrated, which can be dangerous.
If you know the water is full of toxic pollutants, then it is very likely not safe to drink, even if it is filtered and boiled.
How water is filtered
A DIY water filter, or any filter, works by putting layers of matter in the way of the dirty water that will actually capture the different particles and pollutants, to produce water that has been purified.
The most common substances to use are sand, which captures the particles, and charcoal, which captures the pollutants.
Different water filters
There are basically two types of water filters you can make, either at home, or out in the wild
The most simple is based on the principle of passing water through a fine, porous substance a number of times to remove particles.
The second type of filter is more of a system through which the water passes slowly, with the particles and pollutants being removed on the way.
How to make a water filter
Simple filtration process
To make this filter, you will need two containers and a finely woven cloth through which water can pass, such as your shirt.
The containers can be anything that will hold water: bottles, bowls, or even hollowed-out logs.
- Fill the first container with water.
- Secure the material over the mouth of the second container.
- Carefully pour the water from the first container onto the material, without spilling any water.
- Wait for the water to pass through the material. Depending on the weave of the material, this may take a while.
- When the water is all in the second container, remove the material and wash whatever has remained behind off.
- Now repeat the process as many times as you need to, by alternating between the two containers.
When the water is clear, it is most probably best to boil it, to remove any remaining pollutants.
Simple filtration system
A filtration system is a series of different types of matter through which water can pass, from coarser matter through progressively finer matter, to remove all the substances of different sizes.
Charcoal is the key
Finely ground charcoal is an excellent part of a filtration system because it absorbs pollutants very efficiently. Charcoal is the result of wood being burned at a high temperature without Oxygen.
There are two types of charcoal you can use:
Activated charcoal: This is charcoal that has added substances and can be bought from most drugstores, some retail outlets, or online.
Ground normal charcoal: This can either be bought at the store, or you can make your own: When your fire has burnt down to coals, cover it with sand, which will smother the Oxygen and allow charcoal to form. Please note that ash is not charcoal, and you cannot use it for a filtration system. The coals must be quite large so that you will make charcoal, not just ash.
When the fire is completely cold, remove the sand and carefully crush the charcoal pieces very finely. This must be done in some kind of container. In the wild, you can use a rock and a piece of bark, or strong leaf.
DIY Water Filter
This DIY water filter is quite easy to make and is something you can do at home, or in the wild with some adaptations.
For the basic DIY water filter system, you will need a container with one wide and one narrow opening, gravel, sand, charcoal and a dense material, through which water can still pass.
The most convenient container to use is a plastic bottle. The measurements of the layers of each material may need to be adapted slightly to fit the size of the bottle.
To make the filtration system:
- Cut the wide bottom of the bottle off, as close as possible to the end.
- Take the lid off the bottle and make a hole in the center. This should only be about two millimeters in diameter.
- Take some absorbent cotton and force it into the narrow end of the bottle. It must be packed densely. Use about an inch (2.5cm) of cotton.
(You can also use a coffee filter here, or even some fabric, as long as it will allow water to pass through.)
- Screw the lid back onto the bottle.
- Pour ground charcoal into the wide end of the bottle. Make sure that there is at least twice as much charcoal as there is cotton.
- Now pour sand on top of the charcoal. This layer should be about the same size as that of the charcoal.
- Pour another layer of charcoal, if you have enough. Again, this should be the same size as the first one.
- Now add gravel to the top of the bottle. This should be quite fine gravel.
- If there is enough space in the bottle, you can add a layer of pebbles or slightly larger stones.
- Remember to leave enough space at the top of the bottle for water, though (about 2-3 inches/5-7.5cm).
- Place the whole filtration system over a container. Try to mount it there, as it takes a while for the water to filter through.
- Pour water into the bottle slowly. Only fill the space at the top of the bottle. Don’t allow any water to spill out.
- As the water passes through the filter, you will need to continue adding water.
This DIY water filter system can be adapted, depending on what you have available.
If you have a bottle, but no knife, you can use a sharp implement like a rock, or even a sharpened stick to get the wide end of the bottle off. The simplest way to do this is to make a series of holes as close as you can in the sides of the bottle, so that it is weakened and can be broken, or forced off.
You don’t have to use the lid of the bottle if you can’t make a hole in it. You can leave the narrow end open, but make sure that the cotton (or what you use) is quite densely packed and won’t come out. Remember that water must still pass through. The simplest thing to do is to cover the narrow opening with a piece of cloth and then pack the cotton (or equivalent) on top of that.
If you don’t have cotton available, you can use a fine substance that can be packed densely. This may be grass (which should be green), or even moss. Make sure that the soil has been washed out of it properly, though.
If you don’t have charcoal available and can’t make your own, because you may not be able to make a fire, you can use different layers of sand. The one that replaces the charcoal will need to be very fine. Take care, though, that the sand does not ‘cake’ and absorb water without allowing it to pass through. (You can experiment before using it.)
If you don’t have a bottle, then you can still make the filtration system, using something that is around you. This can be a piece of bark that can be bent easily, or a large, thick leaf. Fold the bark/leaf around to form a funnel, in which you will make the filter. You can also hollow out a piece of bamboo, or even a log and use that.
If you’d rather purchase a water filter to have on hand, check on these water filters on Amazon.
FAQ
How do I make a water filter at home?
You can make a simple water filter at home by putting progressively finer absorbent layers into a bottle and allowing water to pass through it slowly: gravel, sand, charcoal, absorbent cotton, or a coffee filter.
When do I need to filter my water?
If you can see that the water is not clear and contains small particles, you will need to filter it, because that matter can make you ill.
We all need water to survive. If there are any particles in, though, it can make you ill. To get rid of these particles and any pollutants, you must filter the water, using a simple filtration system. Then you can drink the water knowing it is most likely to help, not hinder.
Raised in a small Arizona town, Kevin grew up surrounded by rugged desert landscapes and a family of hunters. His background in competitive shooting and firearms training has made him an authority on self-defense and gun safety. A certified firearms instructor, Kevin teaches others how to properly handle and maintain their weapons, whether for hunting, home defense, or survival situations. His writing focuses on responsible gun ownership, marksmanship, and the role of firearms in personal preparedness.