Survival 101: How to Purify Water and Save Your Life

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How to Purify Water, water filter, cup

When venturing into the wilderness, finding a reliable source of clean drinking water should be your top priority. Because many natural water sources such as streams and lakes can be contaminated with dangerous bacteria and viruses that can make you sick. That’s why learning how to purify water is crucial for any outdoor enthusiast. In this guide, we’ll show you a variety of effective methods on how to purify water, ensuring you can quench your thirst safely and enjoy your adventure to the fullest.

1. Water Collection

how to purify water - water collection

The first step in learning how to purify water is to collect it safely and carefully but following these guidelines:

a. Find a collection spot:

  • Look for an area that is away from animal grazing areas.
  • Choose a spot on higher ground or close to the water’s source.

b. Choose a suitable water source:

  • Look for moving water like a stream, river, or spring.
  • Avoid stagnant water sources, such as ponds or puddles.

c. Choose a clean container:

  • Use a clean water bottle, canteen, or collapsible water container.

d. Collect the water:

  • Dip your container just below the surface of the water.
  • Try to avoid touching the inside of the container or introducing any debris.

e. Pre-treat the water:

  • Before collecting the water, use a water filter, pre-filter, or a clean cloth to remove larger debris, such as leaves or twigs.

It’s not enough to collect water from any source, as it can contain harmful contaminants that can make you ill. That’s why the next step after collecting water is filtration.

2. Water Filtration:

How to purify water - pump filter

After collecting water from a natural source, the next step in purifying water is to filter it. Water filtration removes small particles, sediment, and some, but not all, bacteria.

Filters with an absolute pore size of 1 micron or smaller can remove parasites like Giardia and Cryptosporidium. However, it’s worth noting that portable water filters may not be effective at filtering viruses or tiny bacteria.

Below, you’ll find several different methods for filtering water:

a. Personal Water Filter:

How to purify water - lifestraw

A personal water filter is a compact and lightweight filtration device you can carry on backpacking or camping trips. These filters typically use a small tube or straw to dip into the water source and suck the water through. The filter removes protozoa and some bacteria from the water as you drink it.

Personal water filters are popular with hikers and backpackers because they are portable, easy to use and affordable. 

b. Pump Filter:

A pump filter is a larger filtration device that you can use to filter more water. These filters use a hand pump to force the water through a filter cartridge. Some high-end models can also remove bacteria, protozoa, and some viruses.

Pump filters are popular for groups of hikers because they can filter greater amounts of water. However, they are heavier and bulkier than personal water filters and can be more expensive.

c. Gravity Filtration:

Gravity filters are popular for basecamps or larger groups because they can filter large amounts of water with minimal effort. They are also easy to use and require no pumping or manual labour. However, they can be bulky and heavy to carry on backpacking trips.

When choosing a water filtration method, consider the size of your group, the length of your trip, and the type of water source you will be filtering. Choosing the suitable filtration method ensures your water is safe and free from harmful bacteria and protozoa.

3. Water Purification

How to purify water - boiling

Even after you’ve filtered your water, there may still be other impurities that need to be removed. That’s where water purification comes in. This involves boiling, using chemical treatments like chlorine or iodine, or employing advanced techniques like UV sterilization or distillation. Taking these extra precautions ensures that your drinking water is free from harmful pathogens and other contaminants.  

a. Boiling

Boiling water is a tried and true method for purifying water. Not only is it simple and effective, but it also requires minimal gear and equipment. Here are the step-by-step instructions for boiling water:

  1. Fill a pot or kettle with the water you want to purify. 
  2. Place the pot on a stove or over a fire. If you’re using a camp stove, follow the manufacturer’s instructions for safe and effective use.
  3. Bring the water to a rolling boil. You’ll know it’s boiling when large bubbles form and rise to the surface. The CDC recommends keeping the water at a rolling boil for at least one minute.
  4. At higher altitudes (above 6,562 feet or 2,000 meters), boil the water for three minutes to ensure that any remaining pathogens are killed off.
  5. After the required boiling time, remove the pot from the heat and allow the water to cool before drinking.

It’s important to note that boiling water won’t remove chemicals or heavy metals. But, it is an effective method for killing off harmful pathogens like bacteria and viruses. For detailed instructions on how to boil water, check out the article on how long to boil water to kill bacteria

b. Chemical Treatment

Chemical treatment is another effective method for purifying water. Chemical tablets and iodine treatments are two of the most common chemical treatments for backcountry water purification.

Chemical Tablets are a highly effective and convenient method of purifying water in the backcountry. These small tablets are lightweight, easy to pack and can quickly turn any questionable water source into clean drinking water. The most common ones contain chlorine dioxide.

To use chemical tablets, fill a container with the water you want to purify. Then, drop the appropriate number of tablets into the water according to the manufacturer’s instructions. 

After adding the tablets, stir the water to distribute the chemicals evenly. Then, let it sit for the recommended amount of time, which can vary depending on the brand and type of tablets you’re using. Typically, the water needs to sit for at least 30 minutes.

To use iodine, fill a container with the water you want to treat and add the drops according to the manufacturer’s instructions. 

The number of drops will depend on the level of contamination in the water and the amount of water being treated.

Stir the water and let it sit for the recommended amount, varying from 15 to 30 minutes, depending on the product. During this time, the iodine will work to kill any harmful organisms in the water.

It’s worth noting that iodine drops are generally unsuitable for pregnant women or people with thyroid issues. 

Chemical water purification in the wild is an effective and convenient way to make drinking water safe. However, chemical treatments may have an impact on the overall taste of the water. 

c. Ultraviolet Treatment

Ultraviolet (UV) treatment is a highly effective method to purify water once it’s been filtered. UV treatment involves using a unique device that emits UV rays to effectively kill microorganisms or penetrate their cell wall to destroy their reproduction ability. One of the benefits of UV treatment is that it does not alter the taste or odour of the water, unlike chemical purification methods. It is also a relatively quick treatment method, taking only a few minutes to complete.

To use a UV water purifier, follow the manufacturer’s instructions carefully. First, fill the water bottle with filtered water, then insert the UV device. Next, turn on the device and stir the water gently for the recommended time, usually around 60 seconds. The device will emit a blue light to indicate that it’s working. Once the treatment is complete, turn off the device and remove it from the water.

d. Distillation

When you find yourself without a nearby water source, solar distillation through evaporation traps can be a lifesaver. By pulling moisture out of the earth, you can create your own source of clean drinking water. The benefit of this method is that it requires no extra tools and it’s low maintenance.

To make an evaporation trap, start digging a hole in the ground and placing a container at the bottom. Cover the hole with a clear plastic wrap, ensuring that the plastic wrap is tight and has no holes. Then place a small rock or weight in the center of the plastic wrap, creating a dip to allow water to collect and drip into the container.

Place the trap in a sunny area, where the heat from the sun will cause water to evaporate from the ground and condense on the plastic wrap. Over time, the condensation will collect in the center dip and drip into the container, giving you a source of clean drinking water.

It’s important to note that this method can take time and may not produce much water. Using a clean container and plastic wrap is crucial to prevent contamination. In the event of an emergency, this technique can be a valuable tool for survival. Pack a container and clear plastic wrap to prepare for such situations.

The Bottom Line

Remember, water is life in the wilderness, and it’s crucial to take every necessary measure to have clean, safe drinking water. And while you’re out there, check out our article on the best way to build a fire to keep you warm and safe during your outdoor adventures.


What are some common methods of water purification?

Common methods include boiling, chemical treatment, filtration, and UV purification.

What are some common contaminants found in natural water sources?

Common contaminants in natural water sources include bacteria, viruses, protozoa, and parasites.

How long do I need to boil water to purify it?

Water needs to be boiled for at least one minute to kill harmful bacteria and viruses.

What types of chemicals can be used to purify water?

Chlorine, iodine, and water purification tablets are commonly used chemical treatments for water purification.

What is the best type of water filter for wilderness use?

A high-quality, portable water filter with a 0.1-micron filter is best for wilderness use.

How do I use UV light to purify water?

UV light purifies water by killing harmful bacteria and viruses. You can use a UV light wand or a UV light water bottle.

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Meet AJ Yarwood, the outdoor enthusiast and the Creative Director of, dedicated to sharing unforgettable outdoor experiences with a twinkle in his eye and a spring in his step. Join him as he navigates the wonders of nature, from towering peaks to hidden trails, sharing a treasure trove of tips and tricks along the way!