Water Filter : Tuna Can Cartridge System




About: Robert started prepping 15 years ago in anticipation of the perceived Y2K crisis. Starting out small with just enough resources to get him and his family through a week of supply disruptions, this quickly tu...

We have seen home made water filters made from recycled water and pop bottles and I have made my share of those and demonstrated to hundreds of school kids.

These are great for emergencies if you need clean water. The only thing with them is that they can be quite clumsy and awkward to make. So I came up with a cartridge system that when one of the elements has passed it's use, you just clean out the tuna tin and put more of that element in and continue using the filter.

Hence the name Tuna can cartridge water filter.

This project is great for teaching it separated each of the filter layers and give them an opportunity to discuss and examine them in depth and I encourage schools, scouts and prepper survival groups to give this a try.

Please pass and share. I look forward to your comments and questions. If you have any comment's or questions please feel free contacting me Survival Central.


Step 1: Gather Materials

Needed Materials

Can opener

3 Tuna Cans

Drill or punch


Fine mesh, cheese cloth or old sock (clean)




Duct tape

Step 2: Open Tuna Cans

Open Tuna Cans

Eat contents or feed to the cat.

I ate tuna for three days and now have had my fill. I don't want to see the 100 or so can I have stored till the Apocalypse.

Once contents emptied, thoroughly clean tins

Step 3: Drill or Punch Out Bottom of Tins

Drill or punch holes 1-2 inches from the center in a circle so you can remove the center of the tin.

Once bottom removed, take your hammer and tap down any burrs that might be left from drilling or punching.

Repeat this step for all three tuna tins.

Step 4: Cut and Insert Mesh, Cheese Cloth or Old Clean Sock

Cut and Insert Mesh, Cheese Cloth or Old Clean Sock making sure that what ever you choose is bigger than the hole you made in the bottom of the tin.

The mesh is there to allow water to flow thoroughly and to make sure that each element of the filter doesn't fall out of the tin.

Repeat this step for all three tuna tins.

Step 5: Add Elements to Tuna Tins

For each of the three tuna tins add the following

1 tin gravel

1 tin sand

1 tin charcoal

Fill each tin leaving about 1/4" to 1/2" at the to so each tin can seat itself properly prior to being taped.

Step 6: Stack and Tape Tins

Stack tins in the following order

Charcoal Bottom

Sand Middle

Gravel Top

Once stacked in that order Duct Tape tins at the seams where the tins meet.

Step 7: Prime and Use of Water Filter

Once you have assembled your filter you will have to prime your filter.

Run water through the filter 3 to 4 times, this will clean out any charcoal dust that might be in the filter from when you made it. This is called priming your filter.

Once filter is primed you can now try out your filter with dirty water. The end result should be cleaner water than what you put in and should be good enough to drink.

Disclaimer: It is in my opinion that even after this filtration process can make the water drinkable, you should also rely on boiling and or chemically treating your drinking water with chlorine tabs or iodine before consumption.

"Be Prepared, Stay Safe and Survive!"



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    22 Discussions


    3 years ago on Introduction

    I know it is probably a silly question, but where do you get the sand if you don't have a beach nearby? I know they sell sand for aquariums and the like. Would that work?

    3 replies

    Onixgato Thanks for the comment and there are no silly questions. You can get the a bag of play sand from Lowes or Home Depot for about $5 a bag. The sand at the aquarium store might cost you more. Thanks again for your question.


    Reply 3 years ago

    do not use play sand, it can contain unsafe chemicals including lead, a better idea is to find a pool supply store, or you can order a bag from ace, but pool filter sand is a finer grade (smaller pieces) non toxic, and designed basically for this use. you could even add food grade diatomaceous earth to the sand for better fines filtration. if you find a pool store, get some salt, chlorine, even bromine, as they're all super useful and people safe products.

    What a great idea, I'm planning on making this. Just one question, The charcoal am I just breaking down the same stuff I BBQ with?

    2 replies

    Reply 3 years ago

    As SJ88 said, definitely do NOT use typical bagged 'briquets', like Kingsford, MatchLight. What we're going for here isn't so much your 1960's TV-dad Weber grill 'charcoal' -- the ideal is really what you'd call "activated carbon".

    So, yeah, you can use one of the more 'natural', all-wood charcoals from the store. Another good way to go is to make some yourself: just heat some chips/chunks of HARDWOOD - oak's a real good choice - real hot in a can, with as little air as possible - you'll get some real nice chunks of carbon with *crazy* surface area to take all the nasties out of the "IN" water. Just fill a big soup can - preferably UNLINED! - with wood chunks/chips, drop the lid back on top, stick it next to the burgers on your BBQ or heat it up on a burner to char (!) the wood inside. [Danger Will Robinson: this makes carbon monoxide - do NOT do it inside!] You can also knock good chunks of black charcoal off the logs in the fireplace -- you want the stuff that's not wood any more, but isn't ash yet -- just the pure, really lightweight, chunks of black gold.

    The reason they're so light? You've gotcherself basically carbon FOAM now (esp. if you used oak so now you have what they call meso- *and* micro-porous morphology - but that's just fancy talk >;-). A chunk of really good 'activated carbon' the size of a sugar cube has the surface area of a few tennis courts - I'm NOT kidding. And all that surface area wants to latch onto the icky bits in the water you're treating.

    Whether you bought, baked, or scavenged the stuff, go ahead and bang it into smaller bits -- you want the water passing/straining through a "bed" of charcoal bits/crumbs, not just trickling over chunks.

    [Oh, yeah, one last cheat alternative: go to the local PetCo or whatever and buy a bagged activated charcoal filter replacement for an aquarium filter, something like a Fluval or Marineland brand. It's, like, *exactly* what you need, the right size, in a filtering 'baggie', real cheap, etc. etc. It's just that making your own 'coal - and putting it in an old nylon stocking or something - IS actually more fun. >;-) ]

    If you are going to use BBQ charcoal don't use the preformed square bricks. They are often treated with chemicals to help them burn better. Us a natural oak type like the one in the picture.


    I love the cartridge idea! This looks like a good alternative to mushing everything inside one container and replacing it all at once. I'm wondering what is the best drill pattern in the bottom of the tin to make use of all your filtering media. I think very small holes spread out over the entire bottom might be more effective. I forget the exact term but if you allow too much water to flow too fast through your filter you can end up with channels inside where the water develops a quick route down a worn out channel. Leaving you with water that isn't as clean is it could be, or worse, water that hasn't truly been filtered.

    3 replies

    Thanks for the comment gravityisweak. This is only the first gen and just thought the mesh was not a bad start.
    I do believe that your suggestion is the best way to go, with small holes throughout the bottom radiating from the center out to a max of about 1 1/2", while keeping the mesh so smaller particulate can pass through the holes.
    It will also help to eliminate the problem you had mentioned about "flow too fast through your filter you can end up with channels inside where the water develops a quick route down a worn out channel"

    Thanks for the suggestions and feedback. I will be updating this Instruct able to reflect the changes you have suggested giving you full credit of course.

    Watch for: Tuna Can Filter 2.0 :)

    Thanks again gravityisweak

    I meant to share a reference with you. This link to an article on pool filters calls it "channeling" there is a little more info here. Obviously drinking water is a little more important than pool water.



    2 years ago

    This is just what I was looking for. I'm going to make mine using a 2 liter bottle upside down. I can either hang it or it will easily sit over a container while the water filters. Just an FYI for some folks who have questions about the charcoal, you can easily make your own, chemical free, charcoal. There are several instructables for it. Thanks for the great Instructable.

    1 reply

    Reply 3 years ago

    It should remove some of the taste it might not remove all though but it will definatley remove some chlorine from city water


    3 years ago on Introduction

    I think you'll need to make it at least twice as big. I assume you are using 6 ounce cans, and your construction method means (as gravityisweak points out) that you aren't using the entire area.

    Because it is so small, you aren't doing much with the gravel- that's just going to catch sticks and leaves, so you could just use the mesh. The real value is in the sand and charcoal, but it will flow through too fast.

    I'd double it up, and then reverse the order. Twice the sand and charcoal would catch a lot more, and if you go gravel->sand->charcoalx2 -> sand -> gravel, you should be able to use the sand to keep the charcoal out of the water, and the gravel to keep the sand out.

    Also, I think you'll want to use smaller gravel, and crush the charcoal for better use.

    2 replies

    Thanks for the comment jkimball and suggestion for the next gen filter, I am already working on. Using both yours and gravityisweak suggestions, I am going to double, then may be triple the number of cans making numerous smaller holes instead of straight mesh. I will still have the mess lining the bottom of each tin. Then I am going to stack the tins as such top to bottom:


    So it acts like a double filter. In the future I am also going to try this with bigger cans.

    Thanks for the input gravityisweak and jkimball stay tuned for project updates.


    Reply 3 years ago

    So this is honestly one of the easiest to understand filtration DIY projects I've come across. Kudos. I think it would work great for a basic rain water collection system I have in mind. I'm not thinking large scale. I'd still insist on boiling the water before drinking but do you think it'd be fine for showering? We have a small pond nearby and my nieces swim there and promptly invade my home smelling of it. I thought creating a small shower area there would be worth it.