When you find yourself in a survival situation and there is no clean water, it's very important to know how to purify and filter the water so you don't make things worse by getting sick. Of course, if you have the opportunity to make preparations ahead of time, you can opt for more practical ways to filter the water during your camping event or even make a permanent water filter in your home.
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Method 1 of 4: Filtering Water While Camping
Step 1. Consider using a physical filter
“Pump Filter” may be one of the least expensive methods in this category for you, but it is time consuming and cumbersome. For longer camping events, try using a “gravity filter,” which is usually a pair of bags connected by a hose. The bag with the filter is filled with water, then hung so that the water flows down through the filter into the other bag, which is empty and clean. This is a quick and convenient method and doesn't require you to carry around a lot of disposable filter supplies.
These filters cannot purify water from viruses, but are effective at filtering bacteria. However, not all wilderness areas need virus protection, especially in the US. Contact your local disease control center or tourist information center for more information about the risks associated with this in your area
Step 2. Learn about chemical disinfectants
Disinfectants in tablet form are slow-acting but inexpensive and effective against most bacteria and viruses. Tablet disinfectants are available in two general types:
- Iodine tablets should be left in the water for at least 30 minutes. These tablets are sometimes sold with complementary tablets to hide the taste of the iodine. Pregnant women and people with thyroid problems should not use this method, and no one should use this method to make their main source of drinking water for more than a few weeks.
- Chlorine dioxide tablets usually have a waiting time of 30 minutes. Unlike iodine, these tablets are effective at purifying water in areas contaminated with the bacteria “Cryptosporidium” - but only if you wait 4 hours before drinking the water.
Step 3. Try UV water purification
UV lamps can kill bacteria and viruses, but only if the water is clear and the lamp is used for a long time. Different UV lamps or UV pens have different intensities, so follow the manufacturer's instructions.
Step 4. Boil the water
This is a very effective way to kill pathogens (disease-causing microorganisms), as long as you let the water boil for at least a minute. Boiling water several times a day may not be practical, but remember that you don't need to do additional filtering if you've already boiled the water for your dinner or morning coffee.
At high altitudes, boil water for at least three minutes, as water boils at a lower temperature in thin air. The high temperature, not the boiling action itself, kills bacteria and viruses
Step 5. Use a stainless steel water bottle
Plastic bottles are designed for single filling and use only, as plastic can decompose over time, adding harmful chemicals to the water, and even becoming a breeding ground for bacteria. Even aluminum bottles are often coated with plastic on the inside, and are not dishwasher safe, making them difficult to clean.
Step 6. Drink water directly from the spring
If you are lucky enough to find a mountain spring bubbling up from between the rocks, the water is usually safe to drink straight from the spring - but this is not the case for water that already flows out of the spring even just 0.6 m from the spring.
This is not a fixed rule, and may be dangerous to do in agricultural areas, areas with a history of mining, or low-altitude areas near population centers
Method 2 of 4: Filtering Water in an Emergency in the Wild
Step 1. In an emergency, use a quick filter
Strain the water through a bandana, shirt, or coffee filter to remove any visible debris. Let the water sit for at least a few minutes, so that any remaining dirt particles settle to the bottom, then pour the water into another container. If possible, boil the water to kill the pathogens in it before drinking. The following steps will teach you how to make a more effective filter, but unless you bring your own charcoal, the process can take several hours.
Step 2. Make the charcoal
Charcoal is an excellent water filter, and is indeed the material used to filter water in many manufactured filters. You can make your own charcoal in the wild if you can make a fire. Make a bonfire out of sticks and let it burn down. Cover it with soil and ash, and wait at least a few hours before digging it up again. Once completely cooled, the charred wood shatters into small pieces, or even into dust. You now have your own charcoal.
While not as effective as store-bought “activated charcoal”, which is impossible to make in the wild, homemade charcoal is effective enough to use as a water filter
Step 3. Prepare two containers
You will need a “top container,” with a small hole in the bottom for filtration, and a “bottom container” to hold the filtered water. Here are some options:
- If you have a plastic bottle, you can cut it in half and use the two pieces for a container. Make a hole in the lid for the filter hole.
- Alternatively, you can use two buckets, one with a hole in the bottom.
- In survival situations with limited equipment, look for plants with bare stems, such as bamboo or fallen tree trunks.
Step 4. Use a cloth to cover the filtering hole in the top container
Stretch the fabric at the base of the top container. Use a cloth wide enough to cover the bottom of the container, otherwise the charcoal may carry the water to the bottom of the container.
Step 5. Put the charcoal on the cloth as tightly as possible
Place the dust and charcoal pieces as tightly as possible on the cloth. For this filter to be effective, the water must drip slowly through the charcoal. If the water flows easily through your filter, you will need to try again and pack more charcoal as tightly as possible over the cloth in the top container. The result should be a thick layer of densely packed charcoal - up to half the height of the container, if you use a water bottle as your filter.
Step 6. Cover the charcoal with gravel, sand, and cloth again
If you have leftover fabric for a second layer, layer the cloth over the charcoal tightly to prevent the charcoal from stirring up as you pour the water into the container. Whether or not you add extra cloth, small pebbles and/or sand are still recommended to catch larger debris and keep the charcoal in place.
Grass and leaves can also be used, as long as you know that they are not poisonous
Step 7. Strain the water
Place the top container on top of the bottom container, with the pebbles on top and the charcoal on the bottom in the top container. Pour water into the top container and watch the water drip slowly through the filter, into the bottom container.
Step 8. Repeat until the water becomes clear
Often, you will need to filter the water two to three times before all the particles are removed.
Step 9. Boil the water if you can
This filter will remove a lot of toxins and odors, but bacteria can often pass through this filtering process. Boil the water, if you can, for added safety.
Step 10. Replace the above materials from time to time
The top layer of sand will contain many microbes and contaminants that are harmful to health if drunk. After using this water filter several times, remove the top layer of sand and replace it with clean sand.
Method 3 of 4: Choosing and Using a Factory-made Home Water Filter
Step 1. Find out what contaminants are in your water
If you live in or near a major US city, find the information in the Environmental Working Group's database. If not, you may need to contact your water company and request a water quality report, or ask a local environmental group that focuses on water issues.
Step 2. Choose a filter type
Once you know the specific chemicals you are trying to remove from your water by filtering, you can read the descriptions of the packaging or online for water filter products to see if they will be filtered out by the device. Alternatively, use the EWG water filter selection search, or narrow your selection with these tips:
- Charcoal (or "carbon") filters are inexpensive and readily available. It can filter out most organic contaminants, as well as lead, mercury and asbestos.
- Reverse osmosis filters can remove inorganic contaminants such as arsenic and nitrates. These filters are not water efficient, so use them only if you know your water is contaminated with chemicals that carbon filters cannot filter out.
- A deionized filter (or ion exchange filter) removes minerals, turning hard water into soft water. This filter does not remove contaminants in the water.
Step 3. Select the installation type
There are many types of water filters that can be purchased, which are designed to accommodate a wide variety of needs. The following are the most common filter options for home use:
- Water filter pitcher. This is especially practical for households that don't use much water, as you can fill the pitcher once or twice a day and chill it in the fridge.
- Faucet-mounted filters are also handy if you want to filter your tap water, but they can slow the flow of water out of the faucet.
- Over-the-counter or under-the-dish-water filters require modification of the pipes, but are generally durable, so they don't require much maintenance.
- Install a whole-house water filter if your water is highly contaminated and unsafe even for bathing.
Step 4. Install the filter according to the manufacturer's instructions
Each filter should come with instructions telling you how to install the filter so that it works properly. In most cases, installing the filter is fairly easy, but if you have trouble installing it, contact the manufacturer for assistance.
Step 5. Pass the water through the filter
Take some water (not hot water) and run it through a filter. In most cases, water is poured over the top of the filter; the water will then descend through filter mechanisms, where all impurities will be filtered from the water. The clean water flows to the bottom of the bottle or pitcher, or to the bottom of the faucet, depending on the type of filter you have.
- Do not immerse the filter while running water through it. Water that rises back up into the filter can again become unclean.
- Some filters become damaged when exposed to hot water; check the manufacturer's instructions.
Step 6. Replace the filter cartridge as recommended
After several months of use, the carbon filter becomes clogged and can no longer purify water properly. Purchase a new filter cartridge from the manufacturer that also makes the water filter. Remove the old cartridge and throw it away, then install the new cartridge.
Some water filters are more durable than others. Check the instructions that came with the product you purchased for the exact time period, or contact the manufacturer
Method 4 of 4: Making a Ceramic Filter for Your Home Water Supply
Step 1. Prepare the ingredients
Homemade ceramic filters work by filtering water through a layer of porous ceramic. The pores are small enough to filter out contaminants, but large enough to let water pass into a container. To make a ceramic water filter, you will need the following equipment:
- Ceramic filter element. You can purchase wax filters or clay filters for this purpose. These filters can be purchased at online websites or hardware stores. Make sure you choose a filter that meets or exceeds the National Safety Foundation's standards, which determine what percentage of impurities must be filtered out of the water for the water to be potable.
- Two food-quality buckets. One bucket is used for pouring unfiltered water, and the second bucket is used to hold filtered water. Food-quality buckets can be purchased at restaurant supply stores, or you may be able to get used buckets from restaurants in your area.
- Tap. This faucet will be installed on the bottom bucket to access the filtered water.
Step 2. Make a hole in the bucket
In total you will need to make 3 holes: one in the bottom of the top bucket, one in the bottom bucket lid, and a third hole on the side of the bottom bucket (for the faucet).
- Start by drilling a 1.25 cm diameter hole in the center of the bottom of the top bucket.
- Drill a second hole, also 1.25 cm in diameter, in the center of the bottom bucket lid. This hole should exactly line up with the hole in the first bucket. Water will flow from the first bucket through the filter and drip into the second bucket through this hole.
- Drill a 2 cm diameter hole in the bottom side of the bucket. This is where the faucet will be installed, so drill this hole only about 2 inches (5 cm) from the bottom of the bottom bucket.
Step 3. Install the faucet
Following the installation instructions that came with your faucet, screw the back of the faucet into the hole you made in the bottom bucket. Tighten the faucet from the inside and make sure the faucet snaps into place.
Step 4. Install the filter
Install the filter element over the hole in the top bucket, so that the filter sits at the bottom of the bucket with the “edge” coming out through the hole made in the bottom of the top bucket. Place the top bucket on top of the bottom bucket, making sure the tip of the filter also exits through the hole in the bottom bucket lid. The filter is now installed.
Step 5. Strain the water
Pour the unfiltered water into the top bucket. The water will begin to flow through the filter and out through the end of the filter into the bottom bucket. The filtering process may take several hours, depending on how much water you are filtering. When enough water has accumulated in the bottom bucket, use the faucet to transfer the water to the cup. The water is now clean and drinkable.
Step 6. Clean the water filter
Dirt in the water will collect at the bottom of the top bucket, so this should be cleaned from time to time. Remove the filter and use bleach or vinegar to clean it thoroughly every few months, or more often if you use the filter frequently.
Tips
You may see black dots inside your pitcher if you have used the filters that can be purchased at these stores long enough. This is most likely the charcoal from the filter. This is harmless, but can be a sign that your filter needs to be replaced
Warning
- Homemade filtered water may still be unsafe to drink. If you start to feel sick after drinking the water, see a doctor immediately.
- You can't currently filter seawater for drinking, although researchers are looking into this possibility.
