How to Filter and Purify Water for Survival [Full Guide 2023]

In this article, you will learn many different strategies and ways to filter and purify your water in the wild and in survival situations.

You have just learned how to create water sources and gather water from our How To Find Water in the Wild article but don’t have any clue on how to filter that water and purify it. You have heard stories of solo hikers in the wild and how they ran out of water. Time is ticking and you are getting thirsty. 

Health problems are surfacing as you become sluggish and have persistent headaches that make even standing and walking extremely difficult. 

Luckily you remember how to filter and purify the water you have gathered from water sources to ensure that you have potable water. You have also remembered how to create multiple survival water filters.

Let’s dive right in.


Although the water you collect may look clear, drinking untreated water will expose you to a variety of bacteria and parasites that can cause illness.

How do these pathogens reach water supplies? It is often borne by humans and animals (and their waste) who kill, work, bathe, defecate, and even die or have their remains thrown in lakes and rivers, both in the wild and in urban areas with poor sanitation practices.

Giardiasis is a key waterborne disease found in the United States’ wilderness. It’s a protozoan parasite that can cause severe cramping and, worst of all, violent diarrhea in any outdoor environment.

Such waterborne diseases found in the wilds of the world include dysentery, cholera, and a variety of worms, viruses, and bacterial infections. The most common symptoms of these illnesses are similar to giardiasis in that they are mostly intestinal in nature. 

When you’re dehydrated from a survival situation or from backpacking for a few days, diarrhea will escalate the problem and even endanger your life.

It is much preferable to treat any water you drink from the wild or from dubious sources than to risk becoming sick. The only exception is if staying hydrated is critical to your survival. In that scenario, you must consume untreated water.

If you would like to learn how to gather and hunt for food in a survival situation, be sure to check out our Spearfishing For Beginners and How to Hunt with Slingshot articles.

What is the Difference Between Purification and Filtration?

When it comes to discovering and consuming water, the first distinction to make is between filtration and purification. They are not interchangeable.

Water filtration is the removal of particles and certain bacteria from water using a cloth or mesh net — a sieve — through which the water flows.

Water purification is a chemical or ultraviolet (UV) method that renders bacteria and other harmful agents inactive. These purification methods use chemicals (or heat) to effectively deactivate the bad stuff, making it safe for consumption and great in a survival situation.

Drinkable water needs both of those processes at times, but only one at other times. Knowing the difference, on the other hand, will literally save your life. 

If you are backpacking in Africa and believe you just need a filter, you will end up with a deadly disease in your system. So let’s dig a little deeper into the distinctions between the two.


boiling water method

One of the most effective wilderness water purification methods is boiling water. The most powerful way to make clear water safe to drink is to boil it. Most bacteria and microorganisms cannot live in boiling water and will die during the heating process.

Only clear water should be boiled. If you boil water that has been polluted with physical materials such as soil and large leaves, you can also become ill from the heavy minerals that will seep into your water. Even lake water that has been stagnant can be boiled and filtered.

You could have filtered water in as little as 10 minutes if you have a sturdy container and a good fire. Simply allow the water to bubble for at least five minutes before removing it from the flames. 

Allow your water to cool for five minutes after it has been thoroughly boiled. 

If you don’t know how to start a fire, or if you would like to check out different methods to start a fire, be sure to check our How to Start a Fire in the Wild and 5 Best Survival Lighters articles.



You may be shocked to hear that there are a few wild plants that can act as great survival water filters. However, before using these plants, you must have a thorough understanding of them. When learning how to purify water in the wild with plants, a single mistake can have serious consequences.

The flowers and plants mentioned below can be used to extract harmful pollutants from water:

  • Cilantro
  • Plant Xylem
  • Rice and Coconuts
  • Banana Peels
  • Reeds and Bulrushes
  • Jackfruit Seeds
  • Fruit Peels
  • Java Plum Seed
  • Moringa Oleifera
  • Oregon Grape

You can quickly produce safe drinkable water by sealing and soaking your clear water in a bag with these plants. Berberine, an antimicrobial alkaloid, is naturally found in the inner bark of the Oregon Grapevine.

Unfortunately, you won’t find this plant in a tropical or desert setting. Citric fruits and seeds are a perfect replacement, and coconuts are a great source of both water and water purifying materials if you have access to them.

Rock and Sand Layers

survival scenario emergency supplies for the center of the cover

The traditional wilderness DIY filtration method is to layer different materials in a hollow log or bag and let water drip down from the top, through the layers, out through a small hole in the floor, and into a clean jar.

If you’re putting these things in a jar, tarp, or piece of fabric, make sure the bottom is tied off but has a small hole for water to drip into. 

Begin by layering finer materials such as sand, fabric, small pebbles, and so on. Then add some larger rocks and charcoal pieces (if you made a fire). Then, start over with another fine layer, followed by a coarse layer on top of that. 

When you’re finished, it should resemble a layer cake. This will remove impurities in the water as well as some larger bacteria, but not all of them. This method is decent to create drinkable water in a survival situation.

 If you need water damage restoration, check there.

Shirt and Cloth

A well-functioning survival water filter can be made by combining cotton with silk, chiffon, or flannel, but if you don’t have access to all of these we will explain a way to filter with fewer materials.

Filtering water through a cloth will remove debris and soil, but not anything else. Still, if that’s what you’re after, you can purify it afterward and create potable water.

Containers or Plastic Bottles


If you don’t have many other options, put muddy/dirty water in a jar and leave it for about 12 hours. In most situations, the soil and other sediments would sink to the ground, leaving just the clear water on top. This clearly does little to eliminate dangerous bacteria, but it does make somewhat drinkable water.

Water Filtration Straws

LIfestraw straw style of water filter steripen products salty water fruit peels

Survival straws, the most well-known of which is LifeStraw, have exploded onto the market in the last 5 years or so. Check out our full product review and comparison with the Grayl filtering plastic bottles in our Lifestraw Vs Grayl review. 

The idea is that you can drink water directly from the straw (or a container with a straw attached) and it will be healthy due to the different filters found inside. The majority of straws on the market are capable of removing bacteria and protozoa but not viruses. 

They usually lack a purifying factor. Most do, however, have a carbon filter that removes off-flavors and odors. Just make sure to double-check the specifications based on your requirements before making a purchase. 

Bringing one to Africa, for example, hoping you can drink safely from the rivers is not a good idea.

While straws can be costly, the cost per liter of filtered water remains very low (most are good for 700-1,000 liters) when compared to chemical treatments.


Pump and Gravity Filters

Gravity Water Filtration System Sawyer Products Amazon 1

The name is misleading here since several of these commercial filters often purify the water. Many people use a ceramic filter to remove larger pathogens and silver to kill viruses. 

These pump filters are quick, filtering and purifying up to a quart of water per minute, but they require a power source (either your arm or in some cases, a battery).

Gravity filters work more like IV bags; they’re slower, but they don’t need batteries or human intervention. Again, just check the specs on any commercial pump or another filter. 

You’re good to go for any circumstance if it mentions a purifying factor. If not, be aware that it will not remove all danger.

Commercial filters are often larger and bulkier than other alternatives, so they can take up more room in a backpack or survival kit. Although they can be an expensive initial investment, they will last a very long time.

Stone Boiling

hot rocks and kinds of water filters with a place dirt in the wilderness survival circles

There will be a few occasions when you will be stranded in the wilderness without the required materials to boil your water. 

Even if you’re crafty enough to make a clay pot out of riverbed materials, it won’t likely withstand the heat needed to bring your drinkable water to a boil.

To avoid this stumbling block, many desert survivalists have adapted the method of heating rocks to extremely high temperatures before immersing them in water.

You’ll also need a jar for your water that won’t be destroyed by these incredibly hot rocks, but this may be a temporary solution. Gather a few stones, wash them, and place them in the embers of a burning fire.

When the rocks are hot enough, extract them with wooden tongs and put them in your water container. If your water doesn’t start boiling within seconds of dropping the rocks in, you’ll have to keep adding hot rocks before it does or start over.

Larger, hollowed-out rocks have the added benefit in the fact that they can carry water are ideal vessels for this technique.


Use a 2% tincture and add 5 drops per quart of water. Apply 10 drops if the water is gloomy. Allow for a 30-minute rest before drinking. 

Iodine comes in a thin, portable container and has other applications such as treating cuts and warts. This is a must-have piece for any emergency kit or bug-out bag.

Iodine has an unpleasant taste and is not suitable for pregnant women or those who are allergic to shellfish. 

Because of the taste, children are always averse to iodine; keep this in mind whether you’re going backpacking or camping. Iodine is commonly the cheapest and fastest of the chemical processes.

There are also advanced iodine tablets available for purchase that are designed for outdoor enthusiasts like us.


It usually comes in the form of tablets that you simply drop into a liter of water and let the chemicals do their job. Your water will be safe to drink and free of all harmful bacteria after around 4 hours.

The disadvantages of chlorine are that it has a long waiting time and is slightly more costly per usage than other processes. 

On the plus hand, most chlorine dissipates in that 4-hour period, so the taste of the water isn’t adversely affected. It has a longer shelf life as well.


Bleach can be used to purify fresh water in urban emergency survival situations. Most bleaches contain sodium hypochlorite, a form of liquid chlorine. 

Since chlorine is a water purification agent, it stands to reason that bleach could be used.

Household varieties usually contain 5-8 percent sodium hypochlorite — check the label before using, and if it’s higher than that, don’t use it. Add 2 drops per quart with a dropper and set aside for 30 minutes before drinking.

Solar Water Disinfection

minutes of rolling boil heat rocks event of an emergency

Solar water disinfection is also known as SODIS and it uses the sun’s energy to create potable water. If you have a clear water bottle or container, simply leave it in direct sunlight for 12 hours (24-48 on cloudy days), and celestial UV rays can destroy most (but not all) bacteria and microorganisms. 

Some experts recommend leaving water exposed for a full day regardless, just to be on the safe side. It all depends on your requirements. 

Since this UV approach does not always destroy all bacteria/viruses, it is best used for survival purposes only, or in areas where the water is considered to be somewhat safe.

UV Devices

There are numerous devices available that generate UV light artificially in order to kill bacteria and viruses. Some are hand-cranked, while others are powered by batteries. 

Keep in mind that these are not filtration systems, so larger particles or debris in the water may not be removed, and some of those larger particles contain pathogens. 

As a result, when using the UV process, it is best to filter the freshwater first. These devices, including pumps and filters, are larger and heavier than some other choices.

What is the best method out of all of them listed above?

untreated water charcoal number of bacteria extended period bad bugs flavor of iodine easiest way T-shirt

Groundwater in the United States and Canada is almost certainly virus-free. 

As a result, commercial filtration devices, including those that do not actually purify (such as survival straws), will be almost always the most efficient way. In these conditions, the chances of contracting a virus are extremely low.

Filters can be larger and heavier than other methods, so chemical treatments can also work and are particularly common among backpackers and long-distance hikers (like the Appalachian Trail).

When traveling outside of first-world countries, you can always purify in addition to filtering (if needed). This includes tablets, UV devices, and filters that contain a purifying feature.

In wilderness and survival scenarios and there are no commercial filtering or purification solutions available, your first choice should be to boil if you have enough water and fuel. 

If you aren’t able to do that, a layered filter made of natural materials is your best choice for staying healthy and safe.

Final Thoughts

Now that you have learned about many different ways to filter and create potable water in the wild,  you have just improved yourself, and you are now more improved.

Let me know if you found this post helpful in the comments below! Please consider following us on Facebook, Twitter, Pinterest, and Instagram. Also, consider sharing this content and subscribing to get 255 free ebooks or six free checklists.

1 thought on “How to Filter and Purify Water for Survival [Full Guide 2023]”

  1. Thank you for the survival tips; they’re just what we need. That would be great if one could write how efficient the procedure is or how much of the water comes out clean.


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