How to Make an Activated Charcoal Water Filter

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Whether you're venturing into the wilderness or temporarily dealing with dirty water in your plumbing, an activated charcoal filter can make your water cleaner and safer to drink. You can easily make a filter yourself, and doing so is a great way to reuse empty plastic drink bottles. You can make an activated charcoal filter at home and take it with you on your next adventure. If you prefer to travel light, however, you can simply stash some activated charcoal in your backpack and make a filter out of leaves or tree bark.

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Don't Use Grilling Charcoal

When making your own water filter, it's imperative that you use activated charcoal rather than the charcoal you use in your grill. These two substances are not the same. Activated charcoal is much more porous and absorbent than the charcoal briquettes you cook with. Unlike cooking charcoal, the pores on activated charcoal are flushed out and cleaned during the process of making the charcoal. This is not true of cooking charcoal, which can contain many impurities and added chemicals, such as lighter fluid or chemical binding agents.

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Having said that, finding yourself in a survival situation changes the rules a bit. Let's say, for example, that you've gotten lost on a hike and find yourself deep in the woods. You stumble across an old campsite and find charcoal in the fire pit. In a pinch, you can make a water filter using this charcoal. The water won't get as clean, and you run the risk of some chemical exposure from the charcoal, but this may be the better option if your choice is cooking charcoal or contaminated water.

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Things You'll Need

How to Make an Activated Charcoal Water Filter

Step 1: Clean and Prep

In a survival situation, you may not have the luxury of cleaning the components that will compose your charcoal filter. If you make your filter at home, however, you can and should clean all the parts. There is no point in filtering your water through a dirty filter if you can avoid it.

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  1. Create a funnel by flipping an empty plastic 2-liter bottle upside down and cutting off the bottom with a razor knife.
  2. Wash the funnel thoroughly with dish soap. Next wash the container in which you plan to collect the filtered water.
  3. Crush the activated charcoal into small pieces, unless you're using an already granulated charcoal product.
  4. Rinse the charcoal well to remove any dirt or debris and spread it out in a single layer to dry.

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Step 2: Assemble the Filter

Activated charcoal works well and can stand on its own as a water filter if it must. You can get an even more effective filter, however, by adding some extra filtration layers to your water filter. It's important to add them in the proper order for maximum filtration.

  1. Place a coffee filter in the bottom of your funnel that covers the opening. This will keep tiny bits of charcoal or sand from dropping into your water.
  2. Put a layer of activated charcoal on top of the filter. This is the most critical part of the filter, so add your charcoal generously while still leaving room for some prefilter ingredients.
  3. Add a layer of sand to the filter above the charcoal.
  4. Follow the sand layer with some pebbles or gravel. In a pinch, crushed-up brick and even grass can serve as the top layer of your filter.

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Step 3: Fill the Filter With Water

Now that your filter is ready, it's time to use it. Be aware, however, that your filtered water still may not be entirely safe to drink. An activated charcoal filter removes a great deal of impurities, viruses, and parasites, but it can't remove them all. You should still boil the water or treat it with water purification tablets before you drink it if you can. Also note that you should filter water before you need it, as it takes a while for the water to make its way through the filter.

  1. Pour water into the top of the filter.
  2. Prop or hang the filter over a clean water collection vessel of some type. Your activated charcoal filter is gravity fed and won't work if it falls over sideways.

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