27 Ways To Purify Water: Making Dirty Water Safe Again

how to purify water

Think about this for a moment.

We can live for more than a month without food but only 3 to 4 days without water.

Why should you know this?

We cannot live more than a couple of days without water which is why we need to dedicate enough time each day to have access to enough water. An average person needs around one gallon of water per day to stay healthy.

Most of the times we will be in a scenario where there is lots of water around us. You can be next to the ocean, a river, a dam, a lake or even a water stream.

There is only one problem.

It is very likely that the water is not going to be drinkable. It might be infested with disease-causing bacteria or other dangerous chemicals.

So what is the solution then?

The solution is water purification. In this article, I am going to reveal 27 methods that are being used today to purify water.

The good thing is that normal individuals such as yourself can use some of these methods. If you should ever find yourself deserted somewhere, then some of the techniques might come in handy.

Some of the methods might include something as simple as using a cloth or heat to purify water. Other ways will consist of more complicated processes that are being used at scale to produce fresh water to the public.

Let’s see what the consequences of drinking contaminated water are.

Why You Should Not Drink Untreated Water

do not drink dirty water

There are many risks involved in drinking contaminated water. Still standing water which is present in nature are a breeding place for disease causing bacteria and viruses. It is also hard to determine where the water is coming from.

For all you know, you might be ingesting untreated sewage water without knowing it. There is also the risk of the water being contaminated by heavy metals. I have had lead poisoning in the past and it is not fun.

Bacteria And Viruses

Bacteria And Viruses

The most significant health hazard associated with water located in the wilderness is that of bacteria and viruses. The most common water sources that can contain this contamination are water puddles, rivers, dams and open containers with water in them.

The contamination can come from animals that walk by the source and then dumping their feces into the water. The five most common types of disease-causing organisms that live in water are Cholera, Giardia, Cryptosporidiosis, Entamoeba Histolytica, and Shigellosis.

Most of these organisms will cause diarrhea which can also lead to dehydration. Giardia is also a parasite that can cause severe diarrhea. The best way to treat water that is infected with these organisms is by boiling the water and to use chemicals such as iodine and chlorine.

Heavy Metals

Talking from personal experience, you do not want to poison yourself with heavy metals. Most heavy metals such as lead, mercury, arsenic, and cadmium are hazardous even in small amounts. The most common source of heavy metal contaminated water is industrialization.

Some large factories will release lead into the drinking water. Other products such as paint and makeup can also land in the drinking water. Heavy metals have a devastating effect on the body and can damage almost any organ system.

Heavy metals have an affinity for damaging the kidneys, liver, nervous system and also the gut. I have been poisoned by lead before which caused muscle weakness, neuropathy, insomnia and stomach problems. Activated carbon is one of the best ways to remove heavy metals out of the water.

Let’s start with some of the methods that can be used to purify water:



It is the process to which salt or saline water which comes from the sea is turned into fresh drinking water. Desalination is a broad umbrella that covers many other methods for cleaning out the salt from the water.

Drinking salt water does not have a good effect on your body and can cause kidney damage along with dehydration. The most common methods for desalination is distillation, reverse osmosis, and Electrodialysis Reversal.

I have written an article dedicated to the topic of desalination. If you are stranded somewhere next to or on the ocean, then you might want to learn how to turn salt water into fresh drinking water.

Using Filtration

Filtration involves the process as to which larger particles within the water are separated from the water by only allowing the smaller water molecules to pass through a medium. Most filtration systems use the same principle by using different methods and materials.

Activated Carbon (Charcoal)

activated charcoal

Activated carbon or activated charcoal as most people like to call it is very useful at removing heavy metals from water. The difference between ordinary and activated charcoal is that activated charcoal is processed through high temperatures. This event causes the holes inside of the structure to reduce in size which also creates a larger surface area.

The activated charcoal will thus have a larger surface area and will be more porous than regular charcoal. Activated charcoal will absorb most of the contaminants and has a special affinity for heavy metals. Many household filters and municipalities make use of activated charcoal to filter out the water.

Survival Straws

Using survival straws are one of the most natural methods for filtering water. Most of these straws can be used by drinking water straight from the source through the straw. The straw will filter out all of the larger particles, bacteria, and protozoa. The problem with these straws is that it might not filter out smaller organisms such as viruses.

It effectiveness of each straw will also depend on the filtering materials used. Some filtering materials might be able to filter out the smaller organisms. Make sure to check the specs of the straw before purchasing one. These straws are best used for campers, backpackers and preppers.

Commercial Water Filter

Commercial Water Filter

There are many different types of commercial water filters that you can buy. Most commercial water filters will make use of charcoal and ceramic filters which will filter out most of the larger contaminants. Some filters also add sand along with cloth to make the filtering process more efficient.

These filters also have several uses. It can be used on countertop filters that you need to fill yourself, filters that are installed on taps and even whole home systems that will clean out all the water that enters your home. Other commercial filters also include survival straws.

A Piece Of Cloth

If you have nothing else to filter the water with, then a piece of cloth can work. The cloth will only filter out the debris or larger particle but will not be fine enough to get rid of the microorganisms that lurk inside contaminated water.

You can use a cloth to get rid of small pieces of sticks and stones to prepare it for further filtration. You can use any type of clothing that is made out of cotton such as a shirt.

Using Sand As A Filter

Most commercial filters today make use of sand to help filter out the water. Sand filters are also being used industrially where it is known as slow and rapid sand filters. Rapid sand filters are in the shape of a vertical tube.

The tube will be filled with sand, and the coarser material will be used on top of the sand to eliminate the largest particles.

The video above will show you how to build your slow sand filter with an empty plastic bottle, sand, cotton wool, and ground charcoal. The sand particles itself will have pores which might trap some of the smaller contaminants. Some of the rapid sand filters will also make use of pressure pumps to force the water through the sand.

Slow sand filters can also be known as bank filtration if it is used at scale. The sand will be sieved and then broken down into layers where the finest is on top and the sand which is coarse on the bottom. You can also add some gravel along with the coarse sand.

The contaminated water will move through the finer sand into the coarser sand and leak through the gravel to the next step where further treatment will be required to get rid of all the pathogens.

Ceramic Or Clay Pot

Clay or ceramic pots are made of materials that have a natural filtering capacity. It is because it already has pores which will allow for the smaller particles to move through and keep the larger one behind.

This method was used by ancient Egypt to filter water. These porous holes are so small that it filters larger microorganisms such as bacteria and protozoa out of the water. It is also well known to filter out E-Coli and Cholera out of the water.

All you need to do is to pour water inside of the pot and place the pot inside a larger plastic container which will catch all of the clean water. It is a prolonged process so make sure to do this in advance.

Membrane Filtration

Membrane filtration is all about synthetic membranes with pore inside which will filter out contaminated water. The pores inside these membranes are around 0.2 μm to 0.5 μm in diameter which will block out most bacteria.

Most factories involved with water purification make use of membrane filtration. Reverse osmosis also makes use of membranes. Nanotechnology has allowed us to make some of the most effective membranes which include the Graphene-Based Sieve and Metal-Organic Frameworks.

Reverse Osmosis

This method is used when dirty water is forced through a semipermeable membrane. Most desalination plants are using this method today. Some commercial purification systems also make use of reverse osmosis to clean the water.

One major drawback is that the membranes need to be continuously cleaned and replaced. The process of reverse osmosis can filter out most of the bacteria, viruses and other inorganic chemicals.

Heat And Solar

Heat and solar play a significant role in the cleansing of water. You can boil water with heat which is one of the best ways to kill all of the organisms. Solar evaporation is also a sought after method for survivalists to clean water.

Boiling Water

boiling water

This method is by far one of the most effective ways to clean the water if you are in the wilderness. You might have to filter the water with a cloth or your shirt to get rid of all the larger particles. No single pathogen can survive when exposed to high heat.

At sea level water will start to boil at 100 °C which is far above microbes maximum temperature for survival. The higher in altitude you go, the longer you have to boil the water. The ideal time to boil water is around 5 to 10 minutes, and it should be allowed to cool off.

It is important to note that boiling water will not remove any heavy metals. If you are in the wilderness, then it will be less likely for the water to be contaminated by lead or mercury. If you collect water close to industrial areas, then it will more likely contain heavy metals.

Solar Distillation

solar still

Distillation happens when water release steam or vapor when it gets hot or boils. The vapor or steam will almost be 100% clean water. This method is also useful to remove salt from the water. There are several methods to do solar distillation.

The best method for this is probably using a solar still. It is made out of plastic, and most of them can be packed in a box and then inflated for use. Most solar stills will have a large round container in the middle which will hold all of the dirty water.

The still also need to be placed under the sun otherwise it will not evaporate. When the vapor reached the edges of the inside of the still, it will start to form water droplets. These droplets will begin to run down the sides with the help of gravity. It will then be stored inside the circular reservoir around the edges of the still.

Solar Energy (SODIS Method)

It can also be called Solar water disinfection (SODIS). This method can be accomplished by only using a clear plastic bottle. You need to fill the bottle with contaminated water and place it in direct sunlight for at least a day. The sun must be shining for it to work. If it is a cloudy day, then keep the bottle outside for two days later.

What will happen is the water inside of the bottle will build up enough heat to kill most parasites and bacteria. The water will not be boiling, but when the microorganisms stay inside the water for too long, they will die. The little critters will also be exposed to dangerous levels of UV radiation.

Think of it this way. If your skin cells can die when exposed to 4 hours of direct sunlight (sunburn), then why not the bacteria. Most of them are also single-celled organism that cannot tolerate too much heat.

Ultraviolet Light

The best way to use UV light to clean the water is to filter it first. You need to get rid of the larger particles so that the pathogens cannot hide inside them. The wavelengths of UV light is very short and will kill the pathogens over time.

The UV light will start to disrupt the DNA of the organisms. It will also begin to chemical reactions in them which will cause them to die. This method is very effective at the killing of Salmonella and E-Coli. Some parasites might not be affected, and it will not clean the water from heavy metals.

There are many UV devices that you can use for this. Some use batteries, and others are hand-cranked. I would recommend you to expose the water to UV light for at least 5 minutes.

Disinfecting With Chemicals

Numerous chemicals can kill pathogens. The substances will include iodine, chlorine, bleach, fluoride, etc. These chemicals will only kill the pathogens and will not get rid of larger particles and other dangerous chemicals.



This is the most common type of chemical used to disinfect water. You will also be able to buy Iodine tablets at numerous survival stores. These tablets need to be in the water for at least 30 minutes to 1 hour to work. As a rule of thumb, one tablet is enough to treat 1 liter of water.

If you do not have access to tablets, then you can use an iodine tincture. Apply 4 to 6 drops of this tincture to 1 liter of water. Also, remember that Iodine is not safe for pregnant women and people that are allergic to shellfish. This chemical does not taste that good and might put some people off.

Using Bleach (Sodium Hypochlorite)


Yes, you heard right, you can use bleach to disinfect water. The amount that you should use will depend on the concentration of the bleach. If the bleach contains less than 10% sodium hypochlorite, then you should only add four drops to 1-liter bottle water. If it is between 10 and 20%, then you should add two drops for each liter of water.

Make use of a dropper to measure each drop of bleach accurately. Let the water stand for at least 60 minutes before you drink it. If the water is brown, then you should double the dose. Shake the bottle and taste a minimal amount. If you do not get a slight taste of chlorine, then add another drop.


This chemical also contains chloride which can be used to kill all of the germs inside the dirty water. Chloramine contains both molecules chlorine and ammonia. The best type of chloramine to use is monochloramine. There are health studies done to indicate that you can add up to 50 mg/L in water for purification.

You will not use that much, and 4.0 mg/L is more than enough to kill most of the germs. This chemical is not suited for dialysis patients.

Hydrogen Peroxide


Mostly used to treat wounds, it can also be used to disinfect drinking water. Hydrogen peroxide or H2O2 oxygenates the water to such an extent where the microbes will die. It can be toxic to consume in large quantities, but a few drops are harmless.

With a 3 to 10% diluted solution, you can add two drops into your drinking water. You should also allow the water to stand for at least 24 hours before consuming.

Use Plants and Bioremediation

Mother nature has already equipped us with several methods of water purification. It might not be as effective as some of the other filtering methods but is much better than not using any methods at all.

Moringa Oleifera Seeds

Moringa Oleifera Seeds

By crushing the seeds of the Moringa tree, you will have a natural coagulant in your hands. This method will not only clear the water of foreign particles but also kill some of the bacteria.

The best way to use the seeds is in the form of powder. You will mix the powder with the water, and it will join with the solid particles. The particles will then sink to the floor of the water container.

The dosage goes as follows. For every 4 liters of water, you will use one crushed seed for low turbidity. For medium turbidity, you will use one seed for every 2 liters of dirty water. For high turbidity, you will use one seed for each 1 liter of water.

Cactus Leaves

Cactus Leaves

If you are stranded on a desert, then you will be happy to know that you can use cactus plants to filter water. The mucus inside the leaves of the plant will bind with the particles and will form sediment.

It can also be boiled inside of the water where it will form a layer on top that can be quickly skimmed. It is also known to remove some of the heavy metals and organisms that live inside the water.

Use Cilantro


Cilantro is a well-known plant for removing heavy metals out of the water. Some people also like to eat cilantro to detox from heavy metals such as lead and mercury. Cilantro can neutralize the electrical charge of metal ions inside of the body which will then release them from our cells.

Inside water, it will have the same effect but it will also absorb some of the heavy metals. The best way to use cilantro for water cleansing is to take a handful of leaves and put it inside a liter of water. Wait for 30 minutes up to 1 hour and the water is ready to drink.

Pine Tree Branches

Did you know that the branches of a pine tree can turn murky infected water into clean drinkable water? The branches of a Pine tree has a natural xylem filter.

This filter also acts as a transportation system for the water inside the tree. The pores inside the filter are small enough so only water can pass through. This will leave almost 99% of the harmful bacteria behind.

As the water evaporates from the leaves, it will automatically suck water from the roots upwards into the stem and then throughout the tree.


There is also the process called bioremediation where microorganisms are used to clear pollutants out of the water. It is especially useful at removing metals and other dangerous chemicals such as perchlorates.

The bacterial strain that is being used is called Dechloromonas Agitata. This strain can change perchlorate back to chloride which is much safer.

Flocculation And Coagulation

Usually when water is being cleaned out at scale, then there need to be several processes involved in a particular manner to get rid of most of the impurities. The problem is that some contaminants cannot be filtered out by conventional methods. It is in this situation where flocculation and coagulation come into work.

In most cases, the process starts with coagulation when substances such as lime or aluminum sulfate are mixed into dirty water. It will then bind with both organic and inorganic substances will bind together and form clumps.

Flocculation comes after coagulation when the water is being stirred so that the smaller clumps can clash into each other and thus form larger clumps. These larger clumps can also be called “floc” which will then fall to the bottom ready for removal.Enter your text here…


This process often follows flocculation and coagulation. Sedimentation can occur in a large basin or tank. The water will be pumped into the tank or basin and be left to sit.

There needs to be no movement inside of the water. After a while gravity will pull all of the particles down until it forms a layer of sludge on the floor.

The water will stay in the tank for up to 24 hours which give enough time for the sludge to build. The water will then be moved for filtration.

Dissolved Air Flotation (DAF)

This step usually follows after flocculation has occurred. Sometimes the floc will not seperate as easy as expected, and air needs to be used.

Small air bubbles will be blown into the tank from below which will result in the smaller floc particles to rise to the top. Air bubbles will always rise to the top when in water.

The bubble will attach themselves to the smaller floc particles and give it a lift to the top where it can be easily scooped out.

Electrode Ionization

This method is primarily used to desalinate water. It comprises of a negative and positive electrode that attracts ions from the opposite charge.

For instance, the negative electrode will only attract positive ions. The positive electrode will attract negative ions. It might need to go through several other methods before reaching this method.

The zinc-copper system can follow the same principle. It also makes use of different charges that attract the oppositely charged ions. In this case, granules are used instead of electrodes.

This system is very effective at removing heavy metals in the water.


Ozone is used to kill off the majority of the bacteria and viruses that live in water. Ozone is a blueish gas that only has three oxygen atoms. Once the extra oxygen atom is released, it will oxidize the water.

The extra atom makes this molecule unstable and kills most microorganisms on contact. The ozone will be created on the site where it will be released in the water through bubbles.

The drawbacks of using this method are that it is expensive and does not remove larger particles and heavy metals.


It is crucial for us as a human species to invent new and sustainable methods to purify water. Our population is growing each day while our water supply is decreasing.

Have you ever been a situation where you had to filter water for survival?

Please leave a comment below and share with us your experience.

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