Purify Water

When the water you're hoping to drink might be riddled with parasites or bacteria particles, you can't afford to skimp on water purification. Read this wikiHow to learn how to purify your own water.

10 Second Summary

1. Fill a pot with water.
2. Bring the water to a rolling boil.
3. Remove the pot from the heat.
4. Let the water sit and settle.


Boiling Water

  1. Place the water you wish to purify into a pot. Place the pot on the stove and turn the stove on to high. When water boils, any bacteria that may have been living in it will be killed, thus reducing your chance of getting sick when you drink the water.[1]
    • If you are in the wilderness when you need to purify your water, build a fire to boil your pot on. If you do not have a pot, you can use any container that is fire-proof.
  2. Bring the water to a rolling boil. When bubbles begin to appear, it means that the water is starting to boil, but continue heating until the water goes into a hard, rolling boil, then start timing. Continue to boil the water for 5-10 minutes plus 1 minute for every 300m above sea level, up to around 5500m where boiling becomes ineffective, to have the most effect upon any bacteria and other micro-organisms.[2]
    • Boiling water for 1 to 5 minutes will purify it sufficiently. [3] It will kill off the vast majority of organisms living in the water. It also removes some chemicals by vaporizing them. However, be aware that boiling the water will not remove solids, metals, or minerals. Also be aware that the boiling point of water decreases with altitude, so you will not get the same purification effect on a mountain top as you would on a coastal plain. You can boil the water longer or use a pressure cooker to offset the lower temperature.
  3. Remove the pot from the heat. Use caution when handling the pot and water as they are, as you may have guessed, very hot.
  4. Let the water sit and settle. You do not need to do this if you are boiling water that came from a tap and you feel sure that there are no solid items, minerals, or metals in the water. If you let the water settle, any dense items in the water will sink to the bottom naturally, allowing you to drink the pure water from the top.[2]

Creating a Purifying System in the Wilderness

  1. Form a cone out of a strip of bark. Birch bark, or a bark similar to it, is best for creating this filtering system because it is flexible but will keep its shape. Keep in mind that this method will not fully purify the water, but it will reduce the amount of microbes in the water. This method should only be used in extreme emergencies.[4]
    • If you are having a hard time keeping your bark in the shape of a cone, you could try to use a piece of rope or a durable type of grass around it to keep its shape.
  2. Layer the cone. Wildwood Survival suggests layering the cone with sand, charcoal, grass, and gravel (or small rocks.) Charcoal is especially good for removing bacteria. If you had fire, crush up some of the burnt pieces of wood.[4]
  3. Pour the water through the cone and into a container. Do this several times to increase the amount of purification that occurs. Again, this method does not guarantee purification, but it will remove a good deal of the contaminants in the water.

Making a Solar Still

If you are in an area with sun, this method may work for you.

  1. Use a bowl or anything that can hold water and that has a flat surface.
  2. Put a weighted cup into the flat part of the bowl. It must be a cup that doesn't float in water.
  3. Fill the bowl with the dirty water. Make sure not to get any into the cup!
  4. Put clear wrap on top of the bowl. Make sure that it is tightly sealed.
  5. Put a rock or heavy object on top of the clear wrap over the spot where the cup is.
  6. Let this sit in the sun. The sun will evaporate the water, but the water cannot escape, so the water vapor goes to the top of the bowl that is covered in clear wrap. Water then goes toward the weighted part with the rock on top and starts dripping into the cup. Anything that isn't the water is left behind in the bowl. Keep in mind that this can take days, and even weeks sometimes, to happen.

Using a Water Purifier

  1. Use a pump purifier. You can use these types of purifiers in conjunction with a canteen or water bottle when out in the wilderness. These pumps are generally hand held and made out of a synthetic or ceramic cartridge. Most filters have two separate hoses, one for clean water, the other for dirty water. On the hose that pumps the dirty creek or lake water, you may find a foam flotation device that keeps the hose from sinking to the bottom and sucking up the silty bottom water. The pump will have a plunger or lever that can be pulled and pushed so that water is sucked up, run through a series of filters within the plunge, and then pumped out and into your water bottle.[5]
    • There are also pump purifiers that attach to the sink in your kitchen. These pumps can be bought at any home improvement store and are based on the same concept as the hand pump (though attaching it to your sink saves you the time of actually having to pump the water.)
  2. Buy a water bottle with a built in purifier. You can now buy water bottles that have their own filters already built in. These work much like the pumps in that they run the water through a filter before dispensing the water into the bottle.
  3. Use an ultraviolet purifier. These purifiers are very easy to use-- you simply stick the pen of the lamp into the water, wait for the light on the side of the pen to turn green, and then stir the pen around in the water until the light turns off. The UV rays kill any bacteria living in the water so that your water becomes safe to drink.
    • Keep in mind that this purifier doesn’t filter out the now deceased bacteria, but despite their continued presence in your water, they are not dangerous anymore.
  4. Try out a gravity fed purifier. These are filters like the ones used by Brita and PUR. As the name suggests, these filters use gravity to pull the dirty water through a filter and into the reservoir that contains clean water. To use this purifier, all you have to do is pour unpurified water into the dirty water section, and wait until all of the water has run through the filter. Often, these filters will have two sections--one for dirty water, and the other for clean.[6]
    • These filters are best used at home or at a campsite as they are generally pretty large and would be a pain to tote around in the wilderness.

Using Purification Tablets

  1. Use purification tablets or drops. You can purchase these drops or tablets at sporting goods and adventure stores. Keep in mind that this is not the best tasting method, but protection from bacteria is worth a bitter taste in your mouth.[7]
    • Iodine tablets are the most commonly sold purifying tablets, but you can also use chlorine tablets with the same result. These tablets are most effective when the water you are purifying is 68 degrees F (21 degrees C) or higher. These chemical tablets will kill bacteria living in your water. These tablets are most often used by campers in the wilderness.
    • Pregnant women, women over 50, and people with thyroid problems or taking Lithium should consult with a doctor before using iodine tablets.
  2. Strain the water if it has large particles floating around in it. You can do this by pouring the water through a cloth and into the bottle or container that you will be purifying your water in. The cloth acts as a strainer that removes the particles floating in the water.[7]
  3. Place the tablets in the water. If your tablets or drops came with instructions, follow these now. In general, you will want to use one tablet for each quart or liter of water you wish to purify. Be aware that these tablets generally have an expiration date. If you use them after this date, they are much less likely to be effective. Always check the bottle before using these tablets.
  4. Mix the tablets into the water until they dissolve. They must be completely dissolved so that they can mix most effectively with the water you are purifying. Wait 30 minutes before drinking the water, as the tablets need that time to effectively kill any bacteria in the water.[4]
    • You should also be aware that tablets are generally less effective in water that is very cold. If the water is 40 degrees F (4 degrees C), you should wait at least an hour after the tablets have dissolved before drinking the water. You can place the water in the sun to warm it up before using the tablets if you have the time to do so.[7]
    • To lessen the strange taste the tablets give the water, add flavoring to the water (if it is available to you.) Powdered lemonade mixes or a pinch of salt will mask the tablet flavor.


  • Commercial filters made for tap water may only remove basic minerals to make it taste better, depending on the quality of the particular filter. They may not remove parasites or other threats that are removed in water treatment facilities. Check the label to be sure of what you're getting.
  • Water that's collected through condensation (such as from plants or soil) needs to be purified. The process of evaporation leaves some sediments behind, but unless boiling temperature is reached, parasites and other harmful substances may still be in the water.
  • Both bleach and iodine work much better in warm water.


  • All the methods indicated above are designed to remove biological threats only, such as bacteria. They generally do not remove chemical (for example, industrial waste such as aluminum sludge) or radioactive contamination. If it is suspected that the water contains such contaminants, rely on distillation, or weigh consumption against the risk of being dehydrated.
  • Chlorine and iodine are toxins. Do not use more of either chemical than indicated, and use only in emergency situations.

Things You'll Need

  • Suitable water container
  • Clean cloth
  • Iodine or chlorine tablets
  • One of the filters listed above
  • A pot
  • A stove or fire
  • Bark, charcoal, sand, grass, and gravel

Related Articles

Sources and Citations