How to Filter and Purify Water

You can filter and purify water with a variety of materials, from leaves to charcoal.

The “how to purify water naturally” is a guide that will teach you how to filter and purify water. This article also includes helpful websites.

Turning on the tap provides most people in the developed world with a drink of safe, clean, and tasty drinking water.

Obtaining potable water outside of the comforts of home, on the other hand, might be more difficult and time-consuming.

Maybe you went hiking with all the necessary gear but forgot to bring enough water for the trip. Alternatively, you may be visiting a developing nation and have been advised not to drink from the tap. Perhaps the SHTF, and you’re stranded in a city without access to safe drinking water (or, less apocalyptically, you’re merely living in a town where the water supply has been temporarily poisoned).

In these conditions, how would you get clean drinking water?

For each of these instances, the best methods may change, depending on where you are, your budget, how long you need your filtering materials to last, and so on.

There are several alternatives for filtering and purifying water, and regrettably, some of the terminology associated with them is also unclear and not often standardized (especially on the web).

So, for camping, survival, and travel, I’ve put up a quick primer on water filtration and purification. I go through the dangers of drinking untreated water, the terminology to know when studying and shopping for filtration and purification systems, and the benefits and drawbacks of the various options. Finally, I provide a quick overview to the most effective strategies for different instances.

Drinking Contaminated Water: Risks and Consequences

Through the use of unclean water, a variety of germs and parasites may be consumed and cause sickness.

How can these pathogens find their way into water supplies? It’s spread by people and animals (and their waste) who hunt, live, bathe, defecate, and even die or have their remains dumped in lakes and rivers in both the wild and inhabited regions with inadequate sanitation procedures.

Giardiasis is a common waterborne infection in the United States’ wilderness. It’s a protozoan parasite that may produce severe cramps and, worst of all, explosive diarrhea in any outdoor setting.

Other watery illnesses found in the wilds of the globe include dysentery, cholera, and a variety of worms, viruses, and bacterial infections. The most prevalent symptoms of these disorders are similar to those of giardiasis in that they mostly affect the intestine. When you’re already dehydrated, whether from a survival situation or simply hiking for a few days, diarrhea can compound the condition and potentially put your life in jeopardy.

Instead of risking a crippling disease, treat any water you consume from the outdoors or from dubious sources. The only exception is if staying hydrated is critical to your survival. If this is the case, you must consume untreated water. Doctors can heal giardiasis, but they can’t treat the dead, as is commonly remarked in wilderness survival circles.

Is it necessary to treat all water?

Rainwater collected in clean containers, as well as melting snow, is typically safe in the wild. Water gathered in the outdoors by transpiration or a still is nearly always safe (if the plant isn’t toxic, of course). If you get the water from somewhere else, such as a stream or lake (moving water is preferable than stagnant water, but it’s still not infallible), dew, or the like, it should be filtered and/or purified since you never know what’s lying in the ground or upstream from your gathering point.


Learn more about how to discover and gather water in the outdoors in a safe manner.

Rainwater in metropolitan locations may not be safe to drink since it has passed through dirty air. If you’re traveling in a developing nation where the safety of tap/well water is in doubt, you’ll want to consume bottled water (which isn’t always an option in rural regions) or filter your water on a regular basis.

Filtration vs. Purification

The first thing you should know about locating and drinking water is the distinction between filtration and purification. They are not interchangeable.

Water filtration is the process of removing dirt and certain microorganisms from water by passing it through a cloth or mesh net – a sieve.

Purification of water is a chemical or ultraviolet (UV) technique that renders bacteria and other hazardous agents inactive. The chemicals (or heat) used in these purification processes effectively deactivate the harmful substances, making them safe to ingest.

Water requires both of these processes at times, and simply one at other times. Understanding the distinction, on the other hand, may literally save your life. If you’re traveling in Africa and believe all you need is a filter, you might wind up with a fatal sickness. So let’s look at the differences between the two in greater detail.

Filtration of water

Some germs can be removed by using a water filter, particularly one that has been professionally tested (rather than the do-it-yourself backwoods kind). But not all of them. Filters can remove protozoa and bacteria from the water, but they can’t remove viruses since they’re too tiny for the mesh to capture.

In general, water in the United States and Canada is certified as safe for filtration-only systems and devices for camping and survival reasons; this is particularly true in mountainous places. When people become ill when trekking or camping and blame it on the water, it’s commonly discovered that the problem is due to poor sanitation (not washing hands, not disposing of waste properly or far enough from campsite, etc.).

Water that has been filtered offers the optimum taste. While other purification processes change the flavor and/or take up to a few hours to make the water safe, your H2O will taste natural and be instantly drinkable.

The basic line is that filters remove pollutants from water, such as dirt and small germs, but they aren’t totally successful in making it safe to drink. If it’s your only option, you’ll probably be OK, but be aware that unpleasant outcomes are still a possibility.

Purification of Water

By deactivating all dangerous organisms, including viruses, water filtration renders H2O safe to consume. However, purification does not eradicate pollutants. Purified unclean water is still dirty water, and it will very certainly need filtration (that should happen first, actually).

Boiling, chemical agents, and UV radiation are the most common methods of purification. When traveling outside of first-world nations, where viral illnesses are more frequent, this is particularly crucial.

Let’s have a look at some of the many filtration/purification options available.



The most prevalent techniques for water filtration and purification in the wild are listed here, along with some benefits and downsides for each.

Filters Made at Home

In general, DIY filters should only be used when there are no other options. You don’t want to go camping with the intention of filtering your water with pebbles, sand, and dirt. These are simply for the sake of survival. If at all feasible, after filtering using these techniques, you should still cleanse the water (by boiling or adding tablets/chemicals).

I’ve arranged them in order of effectiveness, with the most effective at the top and the least successful at the bottom.

Tubing and wood

Wood and tubing diy water filter.

While this diagram shows a clamp, you’re unlikely to have one in a wilderness survival situation. The combination of wood and tube (or other materials) will suffice.

A water filtration system created from a little piece of wood and tubing is the finest DIY option. You can truly kill 99 percent of germs by using sapwood (the delicate outer layers of a tree) or a short, green branch (but still not viruses). Cut a little piece of sapwood (a couple of inches long by an inch or so broad) and wrap it firmly with some form of plastic tubing if available to construct this filter. You’ll be utilizing the branch as a filter, pouring water over one end and letting it drop into a container from the other, so the tubing will keep untreated water from flowing down the side and into your receptacle. If you don’t have plastic tubing, use cordage, a t-shirt/cloth, or the plastic from a water bottle as a substitute. Then carefully pour little quantities of water onto the branch’s end, allowing the water to filter out the other end. Be aware that this is a time-consuming approach, but you’ll be able to create up to 4 liters of filtered drinking water every day, more than enough for even a couple of people.

Cake with layers of rock and sand. Layering different materials in a hollow log or bag and letting water drop down from the top, through the layers, out through a tiny hole at the bottom, and into a clean container is a traditional wilderness DIY filtering technique.


Diy survival water filter illustration.

The Army’s survival guidebook, FM 21-76.

If you’re storing these products in a bag, tarp, or piece of fabric, make sure the bottom is secured but has a tiny opening for water to drain through. Begin by layering finer materials such as sand, fabric, tiny stones, and so on. Then throw in some bigger rocks and charcoal shards (if you made a fire). Then add another fine layer and a coarse layer on top of that. When you’re done, it’ll appear like a layer cake. This will remove pollutants from the water as well as some bigger bacteria, but not all of them.

Shirt/Cloth. Water filtered through a piece of cloth will remove trash and filth but not much else. Still, if that’s what you’re wanting and you can purify it later, it’ll work.


Container. If nothing else, put muddy/dirty water in a container and let it for around 12 hours. The dirt and other particles will usually sink to the bottom, leaving the clean water on top. This certainly does nothing to eliminate hazardous bacteria, but it does make the water taste better.

Filters for the Commercial Market

Straws for Survival Survival straws, the most well-known of which is LifeStraw, have sprung into the market in the past 5 years or so. The concept is that you may drink water directly from the straw (or a water bottle with a straw attached) and it will be safe due to the different filters within. The majority of commercially available straws can kill bacteria and protozoa, but not viruses. They usually don’t have any purifying properties. Most, on the other hand, feature a carbon filter that eliminates off flavors and aromas. Just be sure to double-check the specifications depending on your requirements before making a purchase. Don’t carry one to Africa, for example, expecting you’ll be able to drink safely from the rivers. This is not a good idea.

Straws are not cheap, but compared to chemical treatments, the cost per liter of filtered water is relatively low (most are excellent for up to 700-1,000 liters).

Gravity Filter/Pump Many of these commercial filters also cleanse the water, thus the term is deceptive. Many people use a ceramic filter to filter out bigger germs and silver to kill viruses. These pump filters filter and purify up to a quart of water per minute, but they do need electricity (either your arm, or in some cases, a battery).

Gravity filters work in a similar way as IV bags; they’re slower, but they don’t need batteries or human intervention. Check the specifications on any commercial pump or other filter. You’re good to go in any circumstance if it specifies a cleansing ingredient. If not, keep in mind that it won’t completely remove danger.

Commercial filters are often larger and thicker than alternative solutions, taking up more room in a backpack or survival kit. While they might be costly up front, they will endure for a very long time.


Water cleansing in the backcountry is usually done by boiling it. According to the Environmental Protection Agency, one minute of rolling boil will destroy all harmful organisms, including viruses. (If you’re at a higher elevation than 5,000 feet, extend the duration to 3 minutes.) Any metal or glass container will suffice, but if you don’t have one, you may melt pebbles over an open fire and set them in your container.

One disadvantage of boiling water is that it necessitates the use of a fire and hence fuel, which isn’t always feasible (though it is easier if you read our article on how to start a fire without matches). It also causes evaporation and a loss of some water volume, which should be considered in cases when every drop counts.

Iodine, chlorine, and bleach are examples of chemicals.

Iodine and chlorine are two common chemical treatments for purifying water that use drops or tablets to disinfect and remove the undesirable material. Bleach is a third alternative for chemical cleansing that is more often seen in urban settings rather than being taken as a wilderness survival item.


Iodine. Use a tincture with a concentration of 2% and 5 drops per quart of water. Add 10 drops if the water is murky. Allow 30 minutes to settle before consuming. Iodine comes in a compact, portable container and may be used to cure wounds and warts, among other things. This is a must-have component for every emergency pack or bug-out bag.

Iodine has an unpleasant taste and is not recommended for pregnant women or people who have shellfish allergies. Iodine is also disliked by many children due to its taste; keep this in mind if you’re going trekking or camping. Iodine is the least expensive and fastest-acting of the chemical treatments.

You may also get specialist iodine pills designed specifically for outdoor enthusiasts.

Chlorine. In most cases, it comes in the shape of pills that you just put into a liter of water and allow the chemicals do their thing. Your water will be safe to drink and clear of any hazardous microorganisms after around 4 hours.

The disadvantages of chlorine include a lengthier waiting time and a somewhat higher per-use cost than other treatments. On the plus side, most chlorine disappears in that 4-hour period, so the flavor of the water isn’t harmed as much. It has a longer shelf life as well.

Bleach. Bleach may be used to cleanse water in urban emergency situations. Sodium hypochlorite is a kind of liquid chlorine used in most bleaches. Because chlorine is a water purifying agent, it stands to reason that bleach might be utilized.

Household variants typically contain 5-8 percent sodium hypochlorite; check the label before using, and don’t use it if it’s greater than that. Add 2 drops per quart with a dropper and let aside for 30 minutes before drinking.


SODIS. Solar water disinfection (SODIS) uses the sun’s energy to clean your water. If you have a transparent water bottle, you can just leave it in direct sunshine for 12 hours (24-48 on overcast days) and the sun’s UV rays will destroy most (but not all) germs and microbes. Some experts recommend leaving water exposed for a full day anyway, just to be safe. It is entirely dependent on your requirements. Because this UV approach doesn’t always destroy all bacteria/viruses, it’s best utilized for emergency situations or in regions where the water is known to be safe(ish).

UV Detectors. There are a number of technologies on the market that produce UV light artificially in order to kill germs and viruses. Some are powered by hand, while others are powered by batteries. Keep in mind that since they are not filtration systems, bigger particles or debris in the water will not be removed, and some of those larger particles may contain diseases. As a result, while utilizing the UV technique, it’s advisable to filter the water first. These equipment, such pumps and filters, are bulkier and heavier than some alternative solutions.

Bottom Line: Which Method Is Best for Different Scenarios?

In first-world nations, for hiking/backpacking: As previously stated, groundwater in the United States and Canada is nearly certainly virus-free. Because of this, commercial filtration devices, even ones that do not cleanse (such as survival straws), will nearly always suffice. In these conditions, your chances of contracting a virus are quite slim.


Chemical treatments, on the other hand, may be bigger and heavier than other procedures, and are particularly popular among backpackers and those performing lengthy through-hikes (like the Appalachian Trail).

For hiking, backpacking, and foreign travel: In addition to screening, you should always cleanse while moving outside of first-world zones (if needed). This includes tablets, UV devices, and filters with a purifying component.

For your bug-out/survival packs, gather the following items: Creek Stewart, our resident survival expert, suggests carrying both a filter and purification tablets in a bug-out or urban survival situation, with boiling as an alternative if time and fuel allow.

For wilderness survival scenarios: You’re stuck in the bush for whatever reason, need to drink water to keep hydrated, and don’t have access to commercial filtering or purifying solutions. Boiling should be your first choice if you have adequate water and fire on hand. Create a wood/tubing filter if you can’t spare the evaporation or can’t get a fire going. If you can’t do that, a multilayer filter made of natural materials is your best choice for staying healthy.

Always keep in mind that filtering only enhances the taste and eliminates contaminants, while purifying assures that the water you’re drinking is free of illness.

Finally, as previously said but worth repeating, it is always preferable to drink untreated water than to perish in the woods!



The “how to filter water for drinking” is an essential skill that should be learned by all. Filtering water will purify it, so you can drink it without the risk of getting sick from bacteria.

Frequently Asked Questions

How do you filter water to purify it?

A: To filter water, you need to put it through a series of filters that are designed for this purpose. There are different types of filters each with their own function and shape. You could use nets on the sides or in front if there is no space for big objects like plants but otherwise they will not be effective at filtering large quantities of water.

Can you purify water by filtration?

A: No, it is not possible to filter water on a molecular level.

How do you filter and purify water for survival?

A: You simply need a filter and some purifying tablets. Filtering water is as simple as filling one of your plastic bottles with the amount of fresh, potable water you want to drink, then pouring that into your survival bottle through the cap opening on top.

Related Tags

  • 10 ways to purify water
  • ways to filter water in the wild
  • ways to filter water at home
  • best way to filter water at home
  • how to filter water without a filter