Introduction: Open Source 3D Printed Water Filter

About: we are an open design lab

Faircap's goal is to provide clean water for everyone, in that vein we are making filtration tools that remove bacteria and viruses. Our aim is to make a $1 water filter, we're hoping to run a crowdfunding campaign to bring the cost down and create a single unit that can filter both chemicals and bacteria and screw onto any standard sized bottle cap.

For researching and learning we came up with a 3d printed version of the Faircap filter. With this project you can fill a bottle full of sludge from a pond, screw the OS3DPWF onto a large plastic bottle, combine it with an ultrafiltration cartridge or leave the filtered water under the sun for 4 hours so that the UV light destroys the DNA from viruses and bacteria, and start pouring your family clean and safe cups of drinking water!

750 million people globally don't have access to clean water and every year the problem worsens. Faircap is developing a variety of open source water filters to provide clean water access for the bottom of the pyramid and to address the needs of the many.

Faircap is sharing the design files and information needed of this 100% open source version to discover and excite a global group of people to collectively work on a multifaceted global problem. Download the files, print your own Faircap, and be a part of the solution. Collaborate with the project at with your own ideas, the more designers we have creating modifications and variations, the faster we'll be able to bring clean water to everyone, openly.

Step 1: Understand the Process

To make your own safe drinking water, you need to understand how to filter the two main classes of contaminants:

  1. Stuff: Particles and chemicals
  2. Pathogens: Bacteria and viruses

First we'll learn to clear the water of floating matter and chemicals since these affect the taste and can have harmful physiological effects. This is accomplished using activated charcoal. Activated carbon is simply charcoal (which you can gather from an extinguished campfire) that has been mixed with salt (25% solution), left to soak overnight, and rinsed. This is the way to make DIY activated carbon. You can see the activated carbon in our cap in the center image.

Second, we need to clear pathogens. Here are a few ways to do that:

  • Boil the filtered, clear and good tasting water for a full minute
  • Leave the filtered water in direct sunlight for four hours. This is called SODIS (Solar Disinfection). The UV rays can penetrate the transparent water and break the DNA inside the little critters - killing them.
  • Use ultrafiltration (UF) plastic filter cartridges to block passage of pathogens.

In this project we use an ultrafiltration (UF) cartridge with pores so small that pathogens can't penetrate, but water flows through. You can see the UF plastic filter on the left of the photo. We're looking for ways to make our own ultrafiltration filters or portable UV light systems to reduce the filter's cost, and to keep the entire project simple and open source.

As you can see, filtering water is a pretty simple process and doesn't require expensive equipment. You just need to understand the two basic components. There's lots more information at the Center For Disease Control.

Lastly, as long as we're here, download the STL files on this page as we'll need them shortly.

Step 2: Gather Materials and Download Files

Before starting a project, it's always best to gather all the materials you'll need so you don't waste lots of time dashing back and forth to the store.

Things you'll need:

  1. 3D printer
  2. Food grade FDA approved PET plastic filament for the printer
  3. Table salt (the quantity depends on how much charcoal you will make, you need a 25% solution of salt in water)
  4. Charcoal from a campfire or BBQ shop (if you purchase charcoal, make sure it doesn't contain any additives like lighter fuel, or other burn agents)
  5. Cotton swabs
  6. A way to remove pathogens (we use an ultra filtration cartridge, you can also leave the clear filtered water for 4 hours under the sunlight or boild it for 1 minute)
  7. Dirty water
  8. The STL's for the cap (download them from this page)
  9. An empty 5-8 Liter water jug. We used one with a standard outer 44mm thread and 38mm inner diameter. These are common in Europe and the STL files for the thread are designed with this measurements

Step 3: Print the Cap

First install your 3D printer software and open up your STL file.

If this is your first time 3D printing, check out this great introduction to 3D printing instructable. Otherwise the process is fairly simple. Open the STL in your favorite printing software and send the file out. There are alternatives, for instance you can ask a friend to print it or send it out to a production shop like Ponoko.

Step 4: Gather and Make Activated Carbon

Activated carbon has a fancy name, but is really quite simple to make.

  1. Take the charcoal you've collected and crumble it up into small pieces, you want the carbon to have lots of surface area.
  2. Combine your charcoal in a 25% mix of salt with 75% of water and mix it all together.
  3. Let it sit for 24 hours to let the salt penetrate the carbon. This will chemically activate the carbon, opening up the pores even more.
  4. Rinse out the salt water by soaking it in clear water, let it sit an hour and change the water a few times until the remaining water is not salty.

That's it! You now have carbon which is highly reactive and bonds with lots of different organic chemicals. It also physically filters out particles and suspended solids. This is how an activated carbon filter works.

By the way, activated carbon is pretty much the only thing that is inside a 25-dollar store-bought home water filter replacement from known brands like Britta

Step 5: Fill the Cap

You don't need to pour water into a filter tank and wait ages for it to trickle through. With Faircap, you simply fill up a bottle and put on the filter cap. Then you can pour it into a cup.

Remember, the activated carbon filter only takes care of the chemical and material filtration. This can be sufficient in many situations, but if you are concerned about bacteria and viruses in your unfiltered water, refer to Step 1 for some ways to filter the critters out.

You might see some carbon particles in the filtered water. To filter out finer charcoal particles or dust, even though charcoal powder is not toxic, you can place a makeup remover cotton swab in the very top of the cap with the nib. Fill it the rest of the way with the activated carbon (don't worry if it's still a little wet). Finally, screw on the cap on the bottom! That's it. You can now screw your assembled Faircap onto a jug of water and drink away!

Step 6: Use the Cap!

Thanks for making the Faircap Open Source 3D Printed Water Filter! This filter is great for replacing store-bought home filters, makes your water taste great, and also removes potentially harmful chemicals.

Step 1: Fill a jug with water you want to filter.

Step 2: Screw the Faircap you just made onto it.

Step 3: Pour clear water out!

Now you have a portable fresh water maker. But remember it does not remove bacteria and viruses. Leave the filtered water under the sun for 4 hours so that the UV light destroys the DNA of both bacteria and viruses. We're working on finding portable and cheap ways to do that all in the same system, but really need some suggestions and help. Ideas are most welcome!

Step 7: Microfilter the Bacteria

We hope this project inspires you and shows you how easy it is to purify water. It's insane to think that hundreds of millions of people are regularly getting sick because of drinking dirty water. This is a preventable problem. We hope that in our own small way, we're starting to pave a path for us all to become part of the solution.

Yours in the pursuit of pure water

— Faircap team