How to Purify Water with Charcoal: The Ultimate Guide

While we luckily live in a time where clean water is readily available, there are times when you may find yourself in a pinch and need an option for filtering water. Many of those who consider themselves “preppers” enjoy learning new ways to purify water and create safe drinking water. There are a few ways that you can purify water using materials that you may have around your home, one of which is charcoal. 

Can you purify water with charcoal? Using charcoal as a filter is a great way to remove sand, rocks, dirt, or other unwanted particles from water in addition to boiling it for ultimate purification. Removing these particles is vital to guarantee the water you are drinking is as safe as possible. 

It is always wise to boil water after filtering through a homemade charcoal filter; this can be done easily and helps remove any final bacteria that may be present. To purify water with charcoal, you will need activated charcoal and a few items that most have around their home. Of course, you can find several charcoal filtration systems sold commercially that are great to have on hand for emergencies. 

What is Activated Charcoal?

Before we jump into how to create your filter, we will look at what activated charcoal is and why it is essential for the filtration system. Charcoal is considered carbon and activated charcoal “is charcoal that has been treated with oxygen to open up millions of tiny pores between the carbon atoms” (How Stuff WorksOpens in a new tab.). Using special manufacturing techniques, activated charcoal is highly porous and is used to adsorb odors and substances from liquids or gases. 

We will further discuss how charcoal adsorbs materials, but essentially the material is extremely good at trapping other carbon-based impurities. Some chemicals like sodium, nitrates, etc. are not attracted to carbon, so they will not be blocked as effectively with the charcoal. Essentially, this means that your charcoal filter will remove certain impurities while ignoring others.

How Does Charcoal Adsorb Impurities?

An area of confusion for many who are interested in creating or buying charcoal filters is that they believe the charcoal absorbs impurities, but it actually adsorbs them. There is a significant difference between these two similar words that influence how the filter works. According to Science ABC, absorption is the process in which substances dissolve in an absorbent’s volume, but adsorption is the process in which substances adhere to the adsorbent’s surface. 

When activated charcoal adsorbs impurities, they are stuck and restricted to the surface of the charcoal. An easy way to keep the two terms separated is to remember that a sponge will absorb, and charcoal will adsorb. This process of using charcoal for adsorption dates back to early Egypt when the substance was used to eliminate undesirable elements while manufacturing bronze. 

Understanding the Adsorption Process

Charcoal has an astoundingly porous surface where the billions of carbon atoms are separated by millions of pores. It has a large surface area that allows it to catch and store impurities easily through adsorption. When charcoal is activated, as mentioned, the number of pores magnify, and the ability to purify water is even better. 

When you create a filter using charcoal, the contaminated water will pass through the charcoal and be purged of contaminants. You will only need a small amount of charcoal to purify a large amount of water because the surface area of the charcoal is so impressive. However, the speed at which you purify the water is also a significant factor, as the slower it passes through the charcoal, the better. 

The substances in the water are chemically adsorbed when they move past the charcoal’s surface and attach to one of its pores. Substances that are not likely to be trapped are organic or carbon-based compounds. This means that a substance is chemically attracted when its negative ions are lured by the positive ions of the activated charcoal. The substances not prone to being removed by charcoal are inorganic compounds and those that are chlorine-based. 

It is important to note that charcoal filters will not remove everything that may be present in the water, and you should never rely on them solely. For example, many minerals and other dissolved compounds can pass through and not be adsorbed at all. If you are using the filter for drinking purposes, make sure to take the time to boil any water along with filtering it. 

Also, charcoal filters are only useful for a limited time. The charcoal’s pores will eventually become full of contaminates, and the ability to adsorb is no longer effective; this means you will want to replace the charcoal regularly to ensure proper filtering. 

How to Purify Water with Charcoal

Now that you have a better idea of how activated charcoal actually works in a filtration system, we will jump into what you can do should you find yourself stuck with no safe water. Of course, filtrating your water with a homemade charcoal filter should not your first choice for safe water, but it is a great method to have in mind should you need it. It is also a great learning tool for children to discuss water impurities and the concept of adsorption. 

If you ever find yourself stuck in a situation where there is no option for water purification, we will discuss how you can create a super simple charcoal filter that uses mostly items you may have on hand. As mentioned several times, you will want to boil any water you put through the filter as well before using to guarantee you remove any unwanted bacteria. The last thing you want is to become ill from water that had more impurities than a basic charcoal filter could handle. 

Materials You Will Need

To create your basic charcoal filter system, you will want to gather a few key materials that should be easy to find. If you cannot find the exact item mentioned, look for something similar that you have around your home or in your camping gear. The materials needed are:

  • An Empty Plastic Bottle (Soda bottle, Water bottle, or something similar)
  • A Knife or Sharp Scissors
  • 2 Canteens, Water Cups, Mugs, Etc. 
  • A Clean Piece of Cloth or a Bandage
  • A Handful of Pebbles
  • A Handful of Sand
  • Charcoal 

Designing Your Charcoal Filter

Once you have the materials you need in place, creating your filter is simple. You will want to follow these basic steps to create a basic charcoal filter:

  • Step 1 – You will want to use activated charcoal if possible, but you can use any charcoal that you may have from your campfire. Make sure that you have whatever charcoal you are using and the other materials needed readily available. 
  • Step 2 – Use your knife or scissors to cut the bottom of your plastic bottle off. You do not want to throw away this part of the bottle, keep it for later usage. 
  • Step 3 – You will want to put a few pebbles into the bottle with the cap still on. Use the end of the knife or a stick to push the pebbles into the bottle, filling any gaps. 
  • Step 4 – Add a layer of sand on top of the pebbles. Use the back of your knife or a stick once again to make sure the sand is packed down, and everything is tidy. 
  • Step 5 – Add a piece of cloth, bandage, or other material and straighten it on top of the sand. 
  • Step 6 – Add your charcoal on top of the cloth. If you are struggling to fit all the materials, you may have to smash it down slightly to have it fit inside the bottle. 
  • Step 7 – Add a second piece of cloth, bandage, or material on top of the charcoal layer. 
  • Step 8 – Add another small amount of sand on top of the cloth. 
  • Step 9 – Finish off the filter by adding a tad more pebbles on top. You should essentially have a layered filter with the charcoal placed in the middle. 

How to Use Your Filter

Now that you have your charcoal filter created, you will want to use it to filter out your water. Though this filter has been proven to be very effective, you do want to remember it will not get rid of everything in your water. You want to do a final boil of any water you put through it to make sure that you remove any bacteria. 

To use your filter, you will want to use one of the cups or canteens you have gathered to collect some water from a stream or nearby water source. The best way to make sure your filter is effective is to get water from a relatively clean source. You also want to get water from the top of the water source, never dip down low, and get a lot of sand or dirt. 

Put your empty canteen or cup underneath your water purifier and begin pouring the dirty water from the canteen through your filter. You may notice that the resulting water still has a cloudy or dirty look, you may have to run it through the filter a few times to remove as many impurities as possible. You should notice a vast difference after a few runs through the filtration device. 

Tips for Optimum Purification

You will want to follow the directions closely to guarantee that your filter works as effectively as possible. Also, there are a few key tips you can keep in mind while creating and using the filter to get the best results possible. Some tips to keep in mind when designing your charcoal filter are:

  • Never forget the cloth pieces in your filter. The cloth is almost as important as the charcoal itself because it helps block out any impurities. If you do not add the cloth, the resulting water will be dark due to the charcoal. 
  • When choosing your pebbles and sand, you will want to remove as much dirt and dust as possible. You can run the pebbles under the water source to rinse off any extra dirt before adding them to your filter. 
  • If you do not have any sand readily available, you can omit this layer. You will simply want to replace the sand layer with another layer of cloth and pebbles. 
  • A 2-liter plastic bottle is one of the best options for the filter because they are large enough to hold the materials. You can also add a handle near the open end of the bottle to make the filtration device easier to hold. 
  • If you want to make your filter even more effective, you can add a layer of cloth or bandage inside the plastic cap and cut a small hole in the cap. While this clearly takes longer for the water to filter through, it can lead to much cleaner water at the end. 

Watch Your Charcoal Filter in Action

If you want to turn your charcoal purifier into a science experiment for your children, this is a great way to talk about adsorption and water purification. You can create a very similar filter system that allows you to see the water purification in action; this is a great way to see how effective the charcoal is and is a simple process. 

To create your simple filter for scientific purposes, you will need very similar materials. These materials include:

  • A Plastic Bottle (preferably a 2-liter bottle)
  • A Knife or Scissors
  • A Measuring Cup
  • Spoon
  • Stopwatch
  • Pencil and Paper
  • Filtering Items like Activated Charcoal, Gravel, Sand, Cotton Balls, Etc.
  • A Filtering Material like Coffee Filter, Napkin, Paper Towel, Cloth, Bandage, or Bandanna

Many create their own “dirty” water for this to ensure that it is easily noted how many impurities are removed. You can add coffee grounds, dirt, leaves, cooking oil, or other pieces of debris to your basic tap water; this is a fun step for children and makes the filtering aspect of the charcoal easily seen. 

How to Create Your Filter Experiment

Creating this filter experiment is super simple and very similar to our previously mentioned filter. To this, you will follow these steps:

  • Step 1 – Cut the bottle in half. Flip the bottles top half over and place it inside of the bottom half, essentially the top half will serve as a funnel into the bottom half. The filter is built into the top part of the bottle. 
  • Step 2 – Place the coffee filter or other material against the opening, where the cap would be, area of the bottle. 
  • Step 3 – Add your cotton balls, charcoal, gravel, sand, etc. in layers. You can use just one filter or layer several, depending on what you have available. The important factor is adding your layer of charcoal to remove any impurities. 
  • Step 4 – Stir and measure out a cup of the “dirty” water that you created. Pour the cup of water into your filter and start your timer once you begin pouring. 
  • Step 5 – Time how long it takes for the water to go through the filter and discuss this with your children. 
  • Step 6 – You can take apart the layers of the filter to see what was caught in each layer. You can also redo the experiment using various filter materials and change up their order. 

Understanding the Filtering Process

The longer it takes for the water to move through the filter, the cleaner it will get. If you notice that the water is quickly going through the filter materials, you will notice a larger amount of dirt or debris getting through. You can run the water through the filter a couple of times to see if any other impurities are removed. 

Your children should be able to easily see how the water looked before purifying versus how it looks at the end. You should be able to see the debris added in the filter, and this is a great time to discuss adsorption. Remember, this water is not pure enough to drink from the filter but can be used to water plants around your home. 

Helpful Videos of Charcoal Filters

If you are interested in creating your own charcoal filter, both of the methods above are highly effective and work wonderfully in a pinch. Keeping these methods in mind is great for those who often camp or like to be prepared for all situations. Some great videos that show charcoal filters in action and better explain how to create your own filter in a simple way are:

Benefits of Using Charcoal for Filtering

While these filters are simply designed to use in a pinch, there are several charcoal-based filtering devices on the market today. When you use charcoal, there are many health benefits that come along with the material. In addition to being highly effective for removing unwanted purities, charcoal is honestly just great for the body. In fact, it is one of the quickest growing beauty products and is something many are adding to their daily routine. 

If you want to purchase and add a charcoal filter to your home, there are many positives that come along with these systems. Some basic benefits of charcoal usage are:

It Allows the Good Stuff to Pass-Through

When you use charcoal, there are many minerals that still pass through the filter that can actually be very beneficial. While the charcoal will remove any nasty chemicals and impurities, the material allows good minerals to pass through. Many other filtering systems remove all impurities and even remove important minerals that are healthy for the body. 

As mentioned, activated charcoal filters attract and adsorb unhealthy organic compounds, but allow other minerals to remain in the water. Unfortunately, this also means not all microorganisms are removed, and charcoal is often used along with other filters. 

Charcoal Improves Water Flavor

A common issue many have is that they do not like the taste of tap water, believe it tastes metallic, or do not like the aroma of the water. The taste of tap water is often due to chlorine and other additives that are put in place to kill off bacteria. While adding chlorine is a great way to protect public health, it has greatly impacted the number of individuals who drink tap water regularly. 

If you want to cut down on the number of plastic water bottles you use, filtering your tap water with charcoal is a great option. Charcoal filters can adsorb the chemicals and remove a variety of odors from the water; this makes the water much tastier overall. 

Charcoal Makes Water Healthier

While charcoal is highly effective at removing a large number of unwanted impurities, it can also add back necessary minerals into the water. Activated charcoal can actually add several important minerals like calcium, magnesium, and iron back into the water; this improves the overall water quality. 

Charcoal is Cheap

While many filtration systems can be very expensive, filters created with charcoal are amongst the cheapest available. Charcoal filters are relatively inexpensive to produce, yet just as effective as many others; this makes them a great option for most households. 

Charcoal Filters are Easy to Maintain

Like most filters that need replacement, once the charcoal is used, they need to be replaced for proper filtering. However, their replacement filters are cheap and easy to come by. Also, most charcoal filters are easy to install, and switching out the charcoal is simple. 

Depending on the amount of water you filter and the quality of water in your home, most charcoal filters need to be changed every six months. You should always make a note of the clarity of your water and observe if there are any major changes. Also, the taste of the water is a major factor that will tell you when it is time to swap out the filter; once water becomes less tasty, change the filter out. 

Adding a Charcoal Filter to Your Home

While you can use the DIY filters in a pinch, using these may encourage you to pick up a professional charcoal filter. These are relatively abundant online and at most home stores. They can also be sold as carbon filters, as charcoal is considered carbon as well. 

Carbon filters are common amongst many water filters that can be added to your water tap, or they are also found in filtering water pitchers. Also, some showerheads contain similar water filters for safer showering water. You will find that many of your favorite water filtering systems actually utilize charcoal filters for quality impurity removal. 

Changing Out Your Water Filter

If you purchase a carbon or charcoal filter for your home, you do want to remember that it needs to be changed out regularly. Look for an option that has easy filter changes and that you can do simply every six months. You never want to use a charcoal filter for longer than a year. 

At this point, the charcoal is almost certain to be full, and the collected particles will begin to break free from the charcoal. Essentially, the collected particles will begin to flow into the water supply, and you can actually end up with worse water than before. 

How Effective Are Charcoal Filters?

Most charcoal filters sold on the market today are highly effective at removing chlorine and other impurities. Some are rated to reduce other contaminants and are used in conjunction with other filtering systems. If the water in your area contains high levels of inorganic compounds and dissolved solids, you want to choose a charcoal filter that also uses reverse osmosis. 

Activated charcoal filters are most often best are removing chlorine, bad taste, and odor from the water. Some of the things you can expect to be removed with a charcoal filter are:

  • Bad Tastes and Odors of Tap Water
  • Chlorine
  • Trihalomethanes or THMs
  • Mercury
  • Pesticides and Herbicides

If you purchase a certified filtration system, you can also expect it to remove the following:

  • Iron and Heavy Metals
  • Lead
  • Bacteria

What Items Does Charcoal Not Remove?

While charcoal filters are highly effective at removing a lot of unwanted impurities, they will not remove hard water, fluoride, or total dissolved solids. Dissolved materials like calcium and magnesium will go through the charcoal filter. If you have a charcoal filter that has a smaller pore size, they will remove coliform, cysts, arsenic, iron, heavy metals, and lead.

Unlike other impurities, those listed above do not adhere to carbon, but they cannot fit through the small pores of the charcoal. Several filter systems also add materials to the charcoal to make them even more effective. For example, adding silver to charcoal can kill bacteria. 

Overall, if you are interested in adding an effective charcoal filter to your home, you should do your research into which is most effective. You will also want to be aware of the water conditions in your area so that you are certain the filter you picked works for your needs.

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