Water is essential to life, yet clean, safe drinking water isn’t always readily available.
Whether you’re an outdoor enthusiast, a survivalist, or just aiming to reduce your environmental impact, understanding how to naturally filter a contaminated water supply is a valuable skill.
In this guide, I’ll explain various natural water filtration methods, from basic boiling to complex techniques like desalination.
Let’s dive in!
14 Ways to Filter Water Naturally
Boiling water is one of the oldest and most trusted methods of purifying water. It’s a simple, cost-effective, and highly efficient way to make contaminated water safe for drinking. This method works by killing bacteria, viruses, and parasites, which are the primary causes of waterborne diseases.
- Fill a pot or kettle with water. If the water is visibly cloudy or contains large particles, you may want to remove the larger impurities using a cloth or coffee filter.
- Place the pot on a stove, campfire, or other heat source and bring the water to a boil.
- Once the water reaches a rolling boil, let it continue to boil for at least one minute. If you’re at an altitude of over 2,000 meters (or about 6,500 feet), increase this time to three minutes to account for the lower boiling point at high altitudes.
- After boiling, let the water cool naturally without adding ice. Store the cooled water in a clean, disinfected container with a lid to protect it from further contamination.
Distillation is a powerful method of water purification that can remove a wide range of contaminants, including bacteria, viruses, heavy metals, and salts. Distillation can be performed both indoors, using common kitchen equipment, and outdoors, depending on your resources and circumstances.
Indoor water distillation method using a stove:
- Fill a pot with water. If the water is visibly dirty, you may want to pre-filter it to remove large particles.
- Place a heat-resistant glass or stainless steel bowl in the pot. The bowl should float on the water and not touch the bottom of the pot.
- Invert the pot’s lid and place it on the pot. The inverted lid will act as a condensation surface for the steam.
- Heat the water until it boils. As the water boils, steam will rise, hit the cool pot lid, and condense into water droplets.
- The droplets will then run down the lid and drip into the bowl. This water is distilled and safe to drink.
- Carefully remove the bowl from the pot, making sure not to burn yourself. Allow the water to cool before drinking.
While this method is effective, it requires a significant amount of energy and heat to boil the water and produce steam.
Outdoor water distillation method (stove-free):
- Dig a hole in the ground in a sunny location. The hole should be deep and wide enough to hold a collection container.
- Place a collection container in the center of the hole.
- Cover the hole with a clear plastic sheet, securing the edges with rocks or soil to create an airtight seal.
- Place a small rock in the center of the plastic sheet, just above the collection container. This will create a low point for the condensed water to drip into the container.
- As the sun heats the ground, moisture from the ground and any vegetation in the hole will evaporate, condense on the underside of the plastic sheet, and drip into the collection container.
Outdoor water distillation requires patience. It can take several hours to collect a significant amount of water, but it’s a valuable technique to know in survival situations.
3. DIY activated charcoal filter
Activated charcoal, also known as activated carbon, is a versatile material that’s widely used in water purification. It’s highly porous and has a large surface area, which allows it to adsorb a wide range of impurities from water, including certain chemicals, heavy metals, and even unpleasant tastes and odors.
- Buy activated charcoal. You can buy activated charcoal in various forms, including powder, granules, or pellets. You can also make your own activated charcoal, but this process can be complex and requires high temperatures.
- Choose a container for your filter. This could be a plastic bottle, a glass jar, or even a piece of bamboo. The size of the container will depend on how much water you want to filter.
- Prepare the charcoal. If you’re using charcoal pieces, you’ll want to crush them into smaller pieces and dust. The smaller the pieces, the more surface area they have, and the more effective they’ll be at absorbing impurities.
- Fill the container with the activated charcoal. If you’re using a combination of charcoal dust and pieces, start with a layer of dust at the bottom, followed by the larger pieces. The dust will catch smaller particles, while the larger pieces provide a path for the water to flow through.
- Pour water into the filter. The water should flow through the charcoal and come out the bottom. If the water comes out too fast, you may need to add more charcoal or use smaller pieces to slow it down.
- Collect the filtered water in a clean container. The water that comes out of the filter should be clearer and have a better taste and odor than the unfiltered water.
4. DIY fruit peel filter
The peels of certain fruits have been found to have water-purifying properties capable of removing various impurities from water.
- Collect the peels from citrus fruits like oranges, lemons, or grapefruits. You can use peels left over from eating the fruit or juicing.
- Dry the peels by leaving them in the sun for a few days or baking them in a low-temperature oven. The peels need to be completely dry to be effective.
- Once the peels are dry, grind them into a powder. You can use a blender, food processor, or mortar and pestle for this.
- Place the powdered fruit peels in a cloth or coffee filter and secure it to create a pouch.
- Pour water through the pouch. The powdered fruit peels will bind with various contaminants, removing them from the water.
- Collect the filtered water in a clean container. The water should be clearer and have a better taste than the unfiltered water.
While this method might not be as comprehensive as others, it’s an interesting and natural approach to water filtration.
5. DIY pine wood water filter
This method is particularly useful in survival situations, where traditional water purification methods might not be available. While creating a DIY pine wood filter is a relatively simple process, it does require some basic tools.
- Find a section of pine wood. The wood should be fresh and healthy, without any signs of disease or decay. The sapwood layer, which is the lighter, outermost layer of wood, is the most effective for filtration.
- Cut a section of wood about 2–3 inches in diameter and 6–8 inches long. This will be your filter.
- Hollow out one end of the wood to create a funnel-like shape. This will be the top of your filter, where you’ll pour in the water.
- Attach a tube or hose to the other end of the wood. This will direct the filtered water into a container.
- Pour water into the top of the filter. The water should seep through the wood and come out the other end, leaving many of the impurities behind.
- Collect the filtered water in a clean container. The water should be clearer and have a better taste than the unfiltered water.
6. UV treatment
Ultraviolet (UV) treatment involves exposing water to ultraviolet light, which kills or inactivates bacteria, viruses, and other harmful microorganisms.
- Fill a clear plastic or glass container with the water you want to purify.
- Place the container in direct sunlight. A location with full sun exposure for at least six hours is ideal.
- As the water sits in the sun, the UV rays penetrate the water and kill or inactivate harmful microorganisms.
- After sufficient exposure to sunlight, the water is safe to drink.
It’s important to note that purification by UV light only works with relatively clear water and may not be effective if the water is heavily contaminated or turbid.
7. Sand filtration
Sand filtration involves pouring water through a container filled with sand, which traps particles and some pathogens.
- Fill a container with fine sand. The sand should be clean and free of any contaminants.
- Pour water into the top of the container. As the water percolates down through the sand, particles and some pathogens are trapped in the spaces between the sand grains.
- The water that collects at the bottom of the container should be clearer and have fewer particles than the unfiltered water.
- Over time, a layer of organic matter and microorganisms develops on the top of the sand bed. This layer, known as the “schmutzdecke,” provides additional biological treatment.
8. DIY Portable Sediment Filters
This method involves using a water bottle filled with layers of sand, charcoal, and gravel, so it’s good for those in need of a portable easy-to-make solution.
- Find a clean plastic water bottle. Cut off the bottom of the bottle to create a funnel shape.
- Add a layer of fine sand to the bottle. This will trap smaller particles.
- Add a layer of activated charcoal above the sand. This will absorb certain chemicals and improve the taste of the water.
- Add a layer of coarse sand or fine gravel above the charcoal. This will catch larger particles.
- Finally, add a layer of larger stones or gravel at the top. This will pre-filter the water and catch the largest particles.
- To use the filter, pour water into the top and collect the filtered water from the bottle cap.
9. DIY desalination
Desalination is a process that removes salt and other minerals from seawater, making it safe to drink. This method is particularly crucial in many parts of the world where fresh drinking water is scarce. However, it’s worth noting that desalination can be complex and energy intensive.
Desalination typically involves a process called reverse osmosis. In this process, seawater is forced through a semipermeable membrane under pressure. Here’s how you can DIY it:
- Dig a hole in the ground. The hole should be about 2 feet deep and 3 feet wide, but the exact size can vary depending on how much water you want to produce.
- Place a clean container in the center of the hole. This container will collect the desalinated water.
- Fill the area around the container with seawater. You can also add any other sources of moisture, like wet leaves or nontoxic plants.
- Cover the hole with a clear plastic sheet. Secure the edges of the sheet with rocks or sand to create a seal.
- Place a small rock in the center of the plastic sheet, directly above the container. This will create a low point in the plastic where the condensed water can drip down into the container.
- As the sun heats up the seawater and moisture in the hole, it will evaporate and condense on the underside of the plastic sheet. The condensed water will then drip down into the container.
- After several hours, you can collect the water from the container. This water should be free of salt and safe to drink.
Remember, this method of solar water disinfection can be time consuming and the amount of water produced can be relatively small. However, in a natural disaster or in areas with limited freshwater resources, desalination can be a lifesaver.
Oysters are natural water filters. They filter water by drawing it in through their gills, trapping particles, algae, and other substances in mucus, and then expelling the clean water. The trapped substances are then eaten or discarded. An adult oyster can filter up to 50 gallons of water a day!
However, this method is more suited to improving the health of natural water bodies than for producing drinking water.
Oysters filter water by drawing it in through their gills, trapping particles, algae, and other substances in mucus, and then expelling the clean water. The trapped substances are then eaten or discarded.
- The first step is to source live oysters. You can either purchase them from a reputable supplier or, if you live near the coast, you might be able to collect them yourself.
- Once you have your oysters, place them in the water that you want to filter. Oysters can be placed directly on the bottom of the water body or suspended in the water using oyster bags or cages.
- Let the oysters do their work.
It’s important to regularly check on your oysters to ensure they are healthy and functioning properly. If you notice a significant number of dead oysters, it could be a sign of a problem with the water quality.
Remember, while oysters can significantly improve drinking water quality by filtering out particles and nutrients, they do not remove chemical pollutants or pathogens, so the water should not be considered safe to drink without further treatment.
Certain minerals, like bone char and iron oxide, can be used to filter water. Minerals filter water through a process called adsorption. The contaminants in the water are attracted to the surface of the mineral and stick to it, effectively removing them from the water.
- The first step is to source your minerals. Bone char can be purchased from certain specialty stores or online. Keep in mind that bone char is an animal product and is not suitable for vegans. Iron oxide can be sourced from rusted iron or steel.
- Before you can use your minerals for filtration, they need to be prepared. For bone char, this means grinding it into a fine powder. For iron oxide, this means scraping the rust off the iron or steel and then grinding it into a fine powder.
- Once your minerals are prepared, you can create your water filter. This can be done by adding the mineral powder to a container, such as a plastic bottle with the bottom cut off. The mineral powder should be packed tightly to form a layer at the bottom of the container.
- Once your water filter is ready, you can begin the filtration process. Slowly pour your water into the container, allowing it to pass through the mineral layer. As the water passes through, the contaminants will be attracted to the surface of the mineral and stick to it, effectively removing them from the water.
- Place another container under your filter to collect the filtered water. Once all the water has passed through, you can store your filtered water in a clean, disinfected container.
Although minerals can remove certain contaminants from water, they may not remove all types. It’s essential to use this method in conjunction with other filtration methods for comprehensive water purification.
12. Plant purification
For centuries, plants have been used to purify water. Certain plants, like cilantro, banana peels, cactus leaves, and xylem plants, have properties that allow them to absorb or trap contaminants.
Cilantro, also known as coriander, is a popular herb that’s known for its ability to absorb heavy metals from water.
- Gather a handful of cilantro leaves.
- Crush the leaves and place them in a cheesecloth or coffee filter.
- Secure the ends of the cheesecloth or coffee filter to create a pouch.
- Place the pouch in a container of water and let it sit for several hours. The cilantro will absorb heavy metals from the water.
- Remove the pouch and your water is ready to drink.
Banana peels can be used to remove organic compounds and heavy metals from water.
- Collect a few ripe banana peels.
- Dry the peels in the sun or in an oven until they are completely dry.
- Grind the dried peels into a powder.
- Add the powder to a container of water and stir. Let it sit for a few hours.
- Strain the water to remove the banana peel powder. The water is now purified.
The mucilage in the cactus leaves traps sediment and other particles.
- Collect a few cactus leaves and remove the spines.
- Cut the leaves into small pieces and place them in a container of water.
- Stir the water and let it sit for a few hours. The cactus leaves will sink to the bottom, taking the sediment and other particles with them.
- Carefully pour the water into another container, leaving the sediment and cactus leaves behind.
The xylem tissue in these plants transports water from the roots to the leaves, filtering out bacteria in the process.
- Cut a section of a xylem plant (like a pine branch) and remove the bark.
- Attach a tube to one end of the branch and place the other end in a container of water.
- Suck on the tube to start the flow of water. The xylem tissue will filter out bacteria as the water passes through.
- Once the water starts flowing, you can stop sucking and let the water flow into a container.
Keep in mind that these methods may not remove all contaminants from the water entirely. Ideally, combine them with other methods.
13. Ceramic pots and gravity
Ceramic pots can filter water using gravity. The tiny pores in the ceramic trap particles and pathogens, while safe drinking water seeps through.
- Find a ceramic pot, unglazed and free of cracks or chips. The unglazed ceramic has tiny pores that will trap impurities.
- Cover any hole at the bottom of the pot with a cloth or coffee filter. This will prevent any large particles from escaping through the hole.
- Place the ceramic pot on top of another container. This container will collect the filtered water. Make sure the pot is stable and won’t fall over.
- Slowly pour the water into the ceramic pot. The water will seep through the pores in the ceramic, leaving impurities behind.
- Allow time for the water to drip through the pot into the container below. This process can take several hours, depending on the size of the pot.
- Once the water has filtered through the pot, it’s ready to drink. Remember to clean the pot regularly to keep it effective.
For best use, combine the method with others to obtain a better filtered water. This method may not entirely remove all particles and pathogens by itself.
14. Natural chemicals
Certain natural chemicals, such as iodine and chlorine, kill bacteria and other pathogens, making the water safe to drink.
- Collect the water you want to purify.
- Add five drops of 2% tincture of iodine to each quart or liter of water.
- Stir the water and let it stand for at least 30 minutes before drinking.
- Collect the water you want to purify.
- Add two drops of household bleach per quart or liter of water.
- Stir the water and let it stand for 30 minutes. If the water does not have a slight bleach odor, repeat the dosage and let it stand for another 15 minutes.
These methods can kill many types of pathogens, but they may not remove other types of contaminants like heavy metals or chemicals. Also, they can leave a residual taste in the water. Use these methods in conjunction with others.
We’ve explored a variety of natural water filtration methods, each with its unique advantages and challenges. With these instructions, you can easily make your own water filter in a pinch.
From simple boiling to plant-based purification, nature offers us many ways to filter water at home or in the wild. The choice depends on your needs and resources.
So, here’s to harnessing nature’s tools for clean, safe drinking water for all!
Want to know about water filters? Explore their importance in ensuring a reliable water supply with these extra pieces of information:
- Knowing How to Choose Water Filter Systems: Which Is Best for You?
- How to Dispose of Water Filter Media and Cartridges?
- How to Remove a Stuck Water Filter?
- How to Change the Water Filter on Your Frigidaire
- How to Filter Hard Water: 6 Common Solutions
- How to Clean a Water Filter
- How to Filter Water in the Wild: 8 Practical Methods