How to Filter Water in the Wild: 8 Practical Methods (2024)

Updated on:
January 6, 2024

You can filter water in the wild by boiling it, using survival straws, adding purification tablets, filtering it through plants, and more. Boiling is probably the easiest and most effective, but the others work too.

You’re deep in nature, surrounded by its beauty. But as thirst kicks in, you realize: not all water is safe to drink. 

In the wilderness, knowing how to filter and purify water becomes not just a handy skill, but a vital one. Join us as we navigate the art of turning wild water sources into refreshing, safe drinks, ensuring your adventures remain memorable for all the right reasons.

Let’s dive into turning that stream into a safe sip, keeping your adventures both thrilling and hydrated, by learning how to filter water in the wild.  

Quick Summary

  • Boiling is one of the oldest, easiest, and most effective methods of water purification.
  • Some filtration methods may remove sediment but not viruses or bacteria, so exercise caution and consider combining two or more methods. 
  • Be prepared for any eventuality by bringing lightweight, portable water filters or purification tablets along.

1. Boiling

Boiling has been used for centuries, from ancient civilizations to modern-day campers. It doesn’t require any fancy equipment or chemicals, making it perfect for those unexpected wilderness situations. But while it’s a tried-and-true method, there are some nuances to keep in mind.

Boiling is all about using heat to kill off harmful contaminants. As water reaches its boiling point, the heat starts to destroy bacteria, viruses, and parasites. The magic happens due to the denaturation of proteins and enzymes within these microorganisms, rendering them inactive.

Here’s how you can do it in the wild:

  1. Gather your water. Find the cleanest source possible. Remember, boiling will kill pathogens but won’t remove dirt or debris.
  2. Choose a container. If you have a metal or glass container, great! If not, you can use a hollowed-out rock or even a makeshift container made from bark.
  3. Start a fire. Create a fire pit, gather dry wood, and ignite. If you’re in a situation without matches or a lighter, methods like the bow drill or flint and steel can come in handy.
  4. Boil the water. Place your container over the fire. Once the water starts boiling, let it bubble away for at least one minute. At higher altitudes, increase this time by one minute for every 1,000 feet above sea level.
  5. Let it cool. Remove the container from the fire and allow the water to cool before drinking.

When using the boiling method to purify water in the wild, keep these important factors in mind:

  • Altitude matters: The higher you go, the lower the boiling point of water. This means water will boil at a temperature lower than 100°C (212°F) as you ascend in altitude. So, if you’re up in the Rockies or the Andes, you’ll need to boil your water longer to ensure it’s safe.
  • Taste: Boiling won’t improve the taste of the water. If anything, it might taste a bit flat after boiling. You can improve the taste by pouring it back and forth between two containers to aerate it.
  • Chemical contaminants: Boiling kills living organisms but doesn’t remove chemical pollutants. If you suspect the water source might have chemical contaminants, look for another source or use additional purification methods.

2. Stone Boiling: Heating With Rocks

Stone boiling is as primal as it sounds. It’s a method that involves using heated stones to boil water.

Follow along to purify water like a caveman (cave…person?):

  1. Collect stones. Opt for smooth, dense stones. Porous rocks can trap water and explode when heated.
  2. Heat the stones. Place your chosen stones in a fire. They’ll need to be heated for a couple of hours.
  3. Boil the water. Once the stones are red-hot, use sticks or other tools to transfer them to your water container. The water will start to boil from the stone’s heat. Repeat until the water has reached a rolling boil for at least 10 minutes.

It may not seem practical, but there are a few advantages to stone boiling:

  • Perfect for situations where you can’t place a container directly on a fire
  • Efficient way to heat large quantities of water
  • Tried and tested for thousands of years

3. Plants

Long before the advent of modern technology, humans relied on natural methods of filtering water. One of the most intriguing methods? Purifying plants.

The following plants are particularly useful for purifying water:

  • Cattails: Often found near freshwater sources, cattails can be used to filter out sediments and impurities. The dense structure of their roots traps particles, making the water clearer.
  • Plant xylem: All vascular plants contain xylem, or tissue. Recent studies have shown that the xylem tissue in some plants, including coniferous trees, can filter out bacteria. By fashioning a simple filter using plant xylem, one can achieve impressive purification.
  • Moringa seeds: Native to parts of Africa and Asia, moringa seeds have natural coagulant properties. When crushed and added to water, they attract dirt, bacteria, and other particles, which then settle at the bottom.

Here are general steps for using plants to purify water:

  1. Identify the right plant. Knowledge of local flora is crucial.
  2. Prepare the plant part as required (crushing seeds, cutting xylem tissue, etc.).
  3. Introduce it to the water and wait for the magic to happen. 

Remember, while natural materials like plants can remove many contaminants, they might not eliminate all pathogens. It’s always a good idea to combine plant-based purification with another method, such as boiling.

4. Sedimentation

Sedimentation is all about patience, gravity, and understanding the natural behavior of particles in water. Let’s dive into the world of sedimentation and see how this passive method can be a game-changer in the wild.

At its core, sedimentation is the process where suspended particles in water settle at the bottom of a container due to gravity. Think of it as nature’s way of letting things find their place. Over time, heavier contaminants in the water drift downwards, leaving clearer water on top.

Here’s how you can use sedimentation to filter water in the wild:

  1. Collect water. First, collect the water from your source. Remember, the murkier it looks, the more particles it has.
  2. Let it rest. Pour the water into a container and let it sit undisturbed. This is where patience comes into play. The longer you let it sit, the more particles will settle at the bottom.
  3. Decant the water. Once you’ve allowed ample time for sedimentation (this could range from a few hours to a day, depending on the water’s initial clarity), carefully decant or pour off the clearer water from the top. Be cautious not to disturb the settled sediments at the bottom.
  4. Purify the water further. While sedimentation removes many larger contaminants, it doesn’t guarantee pathogen-free water. It’s always wise to follow up with another purification method, like boiling or using purification tablets.

While it doesn’t remove pathogens, sedimentation has its place for a few reasons:

  • It requires no special tools or chemicals. All you need is a container and some patience.
  • Especially for very turbid or muddy water, sedimentation can drastically improve clarity, making subsequent purification methods more effective.
  • Unlike boiling water or some other methods, sedimentation doesn’t require any energy input. It’s all about letting nature do its thing.

It’s important you keep in mind the following points, though:

  • Sedimentation is more effective for larger particles. Very fine particles, certain pathogens, and dissolved chemicals won’t settle.
  • Always follow up with another purification method to ensure safety.
  • If you’re in a hurry, introducing coagulants like crushed moringa seeds or alum can speed up the sedimentation process.


In a world brimming with high-tech solutions, sometimes the simplest methods stand out. SODIS, or solar water disinfection, is one such method. It’s a technique that transforms the sun’s rays into a powerful water purifying tool. If you’re intrigued, let’s dive into the world of SODIS.

The ultraviolet (UV) rays from the sun are potent enough to kill harmful pathogens present in the water. (In fact, UV is a leading method of residential and industrial water filtration systems.) And the best part? All you need is a clear plastic water bottle and a sunny day.

Here’s how it works:

  • Fill up. Take a clear plastic bottle and fill it with water. Ideally, the water should be relatively clear. If it’s too cloudy, you might need to filter it first using a cloth or another method.
  • Expose to the sun. Place the filled bottle on a reflective surface, like a metal sheet or aluminum foil, under direct sunlight. This ensures that the water gets maximum UV exposure.
  • Wait. Let the bottle sit under the sun for about six hours on a sunny day. If it’s cloudy, you might need to leave it out for up to two days.
  • Drink up. Once the time’s up, the water is ready to drink! The UV rays would have killed off the harmful pathogens, making it safe to consume.

SODIS has several benefits:

  • Eco-friendly: No chemicals, no waste. Just natural sunlight.
  • Cost-effective: No need for expensive equipment or filters. A simple plastic bottle will do.
  • Accessible: Especially useful in remote areas where traditional water purification methods might not be available.

It’s not foolproof. Consider these limitations:

  • PET bottles are ideal for SODIS. They allow UV rays to penetrate and don’t leach harmful chemicals into the water.
  • The clearer the water, the more effective the SODIS method. Turbid water can hinder UV penetration.
  • SODIS relies on sunlight, so it might not be the best method during prolonged cloudy or rainy periods.

6. Survival Straws

Among outdoor adventurers, one tool has been gaining traction for its sheer convenience and life-saving potential. Enter the survival straw: a compact, lightweight, and highly efficient water filtration device. If you’ve ever wondered about this nifty gadget, let’s break it down.

Survival straws, often referred to as personal water filters or emergency straws, are portable filtration devices designed to be used directly from a water source. Imagine bending down to a stream and sipping water through a straw, but with the added assurance that the water you’re drinking is being filtered in real time.

Here’s how they work:

  • Physical filtration: Most survival straws contain a mesh or membrane that physically blocks contaminants like sediment, debris, and even some microorganisms.
  • Activated carbon: Many straws come equipped with an activated carbon element as well. This not only improves the taste and odor of the water but also helps in removing chemicals and heavy metals.
  • Chemical filtration: Some advanced straws might have an iodine or similar component that actively kills bacteria and viruses as the water passes through.

Why opt for a survival straw?

  • They’re lightweight and compact, making them a favorite for backpackers, hikers, and emergency preppers.
  • No waiting time. Just sip directly from the source.
  • Compared to many portable filtration systems, survival straws are relatively inexpensive.
  • No complicated setup. It’s as intuitive as drinking through a regular straw.

Just consider the limitations of survival straws:

  • Each straw filter has a limited lifespan, often measured in gallons/liters. It’s crucial to know this limit and replace the straw when necessary.
  • While many straws can filter bacteria and protozoa, not all are equipped to handle viruses. Ensure you know the capabilities of your straw.
  • While survival straws can handle turbid water, it’s always better to use clearer water sources to prolong the life of the filter.

7. Purification Tablets: Your Pocket-Sized Lifesaver

In the vast expanse of the wild, where every ounce in your backpack counts and every decision can be crucial, water purification tablets emerge as a modern marvel. They’re lightweight, compact, and can turn questionable water into a safe drink in a matter of minutes.

These tablets are typically made of chemicals that disinfect and purify untreated water. The most common active ingredients are iodine, chlorine, or chlorine dioxide. When these chemicals come into contact with water, they release ions that target and neutralize harmful pathogens, making the water safe to drink.

Follow these steps to use purification tablets on your next adventure (or god forbid, in an emergency):

  1. Collect water. As with any purification method, start by sourcing the clearest water you can find. While the tablets will kill bacteria and viruses, they won’t remove dirt or debris.
  2. Add the tablet. Read the manufacturer’s instructions carefully. Typically, you’ll add one tablet to a liter of water, but this can vary.
  3. Wait. Once the tablet is added, shake your water container to mix it in and let it sit. The waiting time can range from 30 minutes to four hours, depending on the brand and water conditions.
  4. Enjoy. After the recommended waiting time, your water is ready to drink. Some tablets might leave a slight taste, which can often be neutralized with a second neutralizing tablet or by adding a pinch of vitamin C.

Purification tablets are great for a few reasons:

  • They’re small and lightweight, making them a favorite for backpackers, hikers, and emergency kits.
  • These tablets are effective against most common waterborne pathogens, including giardia and cryptosporidium.
  • Most tablets have a shelf life of several years, making them a reliable standby.

Here are a few things to remember about tablets:

  • Some users find that certain tablets can leave an aftertaste. This is often a trade-off for the convenience and safety they offer.
  • While the chemicals in these tablets are designed to be safe for consumption in the recommended doses, some people prefer to avoid them due to health or environmental concerns.
  • Tablets are great for biological contaminants, but they won’t remove chemical pollutants or heavy metals. In areas where these are a concern, consider combining tablets with a filter or other purification method.

8. DIY Water Filters

With a bit of ingenuity and some everyday items, you can craft your own water filter. I’ll share three pretty simple DIY water filters.

Basic survival water filter


  • A plastic bottle or a hollowed-out bamboo stick
  • Sand
  • Gravel or small stones
  • Charcoal (from your campfire)
  • Cloth or a piece of clothing


  1. Cut the bottom off the plastic bottle or prepare your bamboo stick.
  2. Start by placing a piece of cloth at the neck of the bottle. This acts as a preliminary filter.
  3. Add a layer of charcoal. This helps remove contaminants and improve taste.
  4. Next, add a layer of sand. Sand acts as a fine filter, trapping smaller particles.
  5. Finally, add gravel or small stones. This layer traps larger particles and debris.
  6. Pour water through your DIY filter. The water that comes out at the bottom is cleaner than before, but remember, this method only filters out larger contaminants. Boiling or using purification tablets is still recommended.

T-shirt filtration


  • A clean T-shirt or any piece of cloth
  • Two containers


  1. Place one container higher than the other.
  2. Drape the T-shirt so that one end is in the dirty water and the other end hangs into the empty container.
  3. The water will travel from the dirty container to the clean one, leaving many of the contaminants behind.

Sock and grass filter


  • A sock (clean, preferably!)
  • Fresh grass or moss


  • Stuff the sock with layers of grass or moss.
  • Pour water through the sock. The grass or moss will trap larger particles.

If you’re in a situation where a DIY water filter is necessary for you to get clean drinking water, well, you’ve probably had a bad day. You still need to remember these important points:

  • These DIY methods are great for filtering out larger particles, but they don’t make water 100% safe. Always boil or treat the water after filtering.
  • If you’re using your DIY filter for an extended period, remember to replace the materials regularly. For instance, change the sand, charcoal, or grass to ensure effectiveness.
  • The beauty of DIY is that you can adapt. No sand? Use fine soil. No cloth? Use a bandana or any piece of clothing.


Venturing into the wild is an exhilarating experience, but it also demands preparedness. As we’ve journeyed through the myriad ways to ensure safe drinking water, it’s evident that nature, combined with a bit of knowledge, provides. 

Whether you’re a seasoned adventurer or a weekend wanderer, prioritizing clean water is paramount. So, the next time you’re amidst nature’s embrace, remember these insights. For a list of qualified filters to take with you on your next wilderness wayfare, see our list of the best hiking filters.

Stay hydrated, stay safe, and let the wilderness continue to inspire. Safe travels!

If you’re interested in gaining more knowledge about water filters, you can check out the guides we’ve made available for you below.

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