After a disaster of any kind, you have to assume the water supply is going to be contaminated. If the water is still running from the tap, you will need to purify it and/or filter it before you drink it just in case the processing plants are offline or some sewage or other toxin has entered the water supply.
If the tap isn’t running, you are going to have to go and find water, which still demands you filter it before drinking.
What if you are in the wild and don’t have a filter with you or you are at home and you don’t have a filter at all? Do you just take your chances and drink the water and hope for the best? NO! Never drink water that hasn’t been filtered.
You can construct an emergency filter with things you find in the environment. You can go big or small depending on your needs and available resources. Filtering water isn’t going to be as effective as purification, but it does remove about 99 percent of contaminants.
The real issue with filters is the fact they don’t always get viruses out of the water simply because viruses are super tiny. Fortunately, in North America, the risk of viruses in the water supply is slim. This isn’t the case for underdeveloped countries and after a major disaster, if sewage systems were to leak, the viruses could eventually find their way into the water supply.
With that said, let’s talk about how to make an emergency water filter in the wild or your very own backyard.
This is when you can be happy about the amount of plastic water bottles that are thrown out every single day. If you are home, you can use an old 2-liter soda bottle or juice bottle. An empty milk jug would suffice as well.
- Plastic container
- Charcoal—you can collect this from a fire pit or a tree that has been hit by lightning. It is best to avoid charcoal that comes from treated or painted wood. The chemicals in the stains and paint would still be present and could be toxic. You can also store charcoal you pick up at the fish store or charcoal tablets.
- Fine gravel—look near dry river beds or dig down a bit, collect it in a separate bowl or container
- Green leaves or plants
- Cotton t-shirt or a bandana
- Cup or bowl to catch the clean water
If you can’t find gravel or you can’t find sand, that is okay. The key ingredient to your filter is going to be the charcoal. The rest of the stuff is just a little extra filtering material.
Build Your Filter
This is the fun part. It is so easy you can have the kids make the filter after you show them how one time.
- Cut off the bottom of the plastic bottle you are going to use.
- Turn the bottle upside down so that the top is facing down. Place a layer of charcoal so that it is on the bottom of the bottle. The amount of charcoal you put in will depend on how big your container is. It should take up about ¼ of the space in the container if you are doing four layers.
- Add a layer of sand on top of the charcoal. The sand layer should be the same thickness as the charcoal layer.
- Add a layer of gravel on top of the sand, again the same thickness for this layer as well. You can do a layer of sand, gravel, sand and then gravel again if you choose. It is all personal preference.
- Add leaves and plants on top of the gravel. Things like dandelions, chickweed, maple leaves or even grass that you know hasn’t been fertilized or treated with pesticide will work. Never use greens that you know to be poison, like poison ivy leaves.
- Place the bandana or t-shirt over the top of the filter, which is the removed bottom of the bottle.
That is your filter! Super easy and truly effective.
Filtering Your Water
Now that you have your filter, it is time to clean your water. Ideally, it helps if you pick out some of the chunky things like weeds, branches and what not before you run it through your filter. The cotton cloth over the top of the filter will help keep out the big stuff as well.
Put a bowl or basin under the bottom of the filter to catch the water. It is a good idea to have two, because you will want to run the water through the filter a couple of times for best results.
Slowly pour the water through the cloth. The water should trickle out the bottom. If it gushes out, your filter isn’t doing its job. The material needs to be packed a little tighter. You want the water to slowly move through each layer. Every layer removes a little more of the bad stuff that will make you sick.
The first run through the filter may result in the water being a little off-colored. Run it through the filter a couple more times to clear it up a bit. Your water is safe to drink at this point.
There isn’t necessarily a technical number of uses this filter is good for, but when the water starts to move faster through the filter, it is a good idea to start over with fresh materials. If you have an abundance of charcoal, making a new filter after cleaning ever 5 to 10 gallons wouldn’t hurt. Set aside charcoal from your campfires to use for filtering.
Keep in mind: filtering is not always a full-proof method of making water safe to drink. If you have a fire and a container to heat the water near the fire, it is best to filter your water and then boil it to make it completely safe to drink.