Having no clean drinking water during an emergency can be fatal and so it's important to know how to make a water filtration system when necessary. Whether you already know how to make one, or you are a first timer, we'll get you familiar with designing a water filter for your needs during a crisis situation. IMPORTANT SAFETY NOTE: These DIY filters are not designed to make drinkable water. No matter how “clean” your filtered water looks, you should never drink it because it still may contain pollutants you can’t see. Drink at your own risk!

MATERIALS NEEDED

• about 2 empty plastic water bottles
• scissors
• towel or paper towels(for spill clean up)
• gauze or cheesecloth to cover the mouth of the hole
• rubber bands
• any materials you think would make a great filter(sand, rocks/gravel, cotton balls, etc).
• *it's okay if you do not have all the materials needed to do this activity, get creative and substitute materials with what you have around the house).*

CREATING A DIRTY WATER SAMPLE

This can be done very easily. All you need to do for this step to prep the water you are going to want to filter. You can mix some soil with water or to make it a little harder of a challenge, you can add some food coloring, oil, vinegar, etc.

BUILDING YOUR WATER FILTER CARTRIDGE

To build your own filtration system, you’ll need a filter cartridge. To do so, start by carefully cutting your water bottle in half, across the width of the bottle. Remove the cap from the bottle. Put gauze or cheesecloth over the opening and secure it with a rubber band. Turn the top half of the bottle upside down (so the part with the cheesecloth or gauze is facing down) and place it into the bottom half of the bottle.

If you want to fit more materials in your filter, you can use two bottles. You can also use larger bottles or try other containers. *Tip: Clear containers will help you see the filtration as it takes place.* It should look something like the picture attached.

DESIGNING YOUR FILTER / TEST AND EVALUATE RESULTS

This step is just adding those items you found around the house to your newly made filter cartridge. Mix or layer the filter materials you have chosen on the top of your filter cartridge. Then, pour your simulated 'waste-water' into your makeshift water filter and observe the water that comes out. You may need to do this a couple of times depending on what type of materials were used when testing the waters. You may notice that some things may need to be improved so that if you were to use something like this during an emergency situation, the water can be as clean as possible. IMPORTANT SAFETY NOTE: These DIY filters are not designed to make drinkable water. No matter how “clean” your filtered water looks, you should never drink it because it still may contain pollutants you can’t see. Drink at your own risk!

PRACTICE MAKES PERFECT

If needed, revise your filter based on what you observed during the 'testing and evaluating' stage. Consider using different types of materials and water amounts. While doing this step, you find that some materials work better than others. Keep testing and evaluating your filter. The goal is to produce as much clean water as possible during a single time through the filter.

sources; 

https://www.jpl.nasa.gov/