How to Purify Water in an Emergency? 5 Simple Methods

How to Purify Water in an Emergency? 5 Simple Methods

Water is one of your most immediate needs in any survival situation, more vital than food or even shelter.

While filtration systems provide easy access to potable drinking water, you might not have access to one in an emergency.

Fortunately, several natural water purification methods are available that require no special equipment and work in practically every type of outdoor setting.

Here’s a closer look at how to purify water in an emergency.

The Importance of Purifying Water

Never drink water from an outdoor source without purifying it first. Even if the water looks clear and clean, it could contain a variety of contaminants such as:

  • Giardia – The result of fecal contamination, giardia causes a variety of gastrointestinal illnesses
  • Bacteria – Common bacterial contaminants include salmonella, E. coli, and campylobacter
  • Viruses – Hepatitis A, norovirus, and rotavirus are transmitted by drinking tainted water.

Women need 2.7 liters, and men need 3.7 liters of water each day.

You can become dehydrated in as little as a few hours, which can result in a lack of energy, mental confusion, and other issues that can affect your ability to survive.

If you’re lost in the woods or otherwise in a survival situation outdoors, even for a short time, you’ll want to immediately focus on finding a source of water.

Here’s how to purify water without using a store-bought filter. 

Boiling Water To Purify Water


Boiling is the easiest and most effective way to purify water if you don’t have a camping filter. Keep the water at a rolling boil for at least three minutes, although most people boil it longer (20 minutes is common).

You can improve the taste of boiled water with a process called re-oxygenation. You’ll need two clean containers. Pour the water between the containers several times, which restores the oxygen. In addition, it helps water gathered outside taste more like tap water.

In an emergency situation, you might not have a fireproof container to hold the water. That’s okay! You can use a method called rock boiling.

  • Use bark to fashion a container for the water. Pine bark works especially well.
  • Make a fire. You’ll need a survival lighter, which you should always carry with you when outdoors.
  • Gather several medium rocks. Clean them off as well as you can.
  • Place the rocks on the edge of the fire so they get hot
  • Once the rocks are hot, transfer them (carefully) into the water container.
  • The hot rocks will cause the water to boil.
  • You’ll need to warm up rocks and continue to add them to the water to keep it boiling for three minutes.

Rock boiling requires the ability to make a fire and the presence of enough vegetation to make some type of container.

While the process of warming the rocks long enough to boil the water can sometimes become frustrating, rock boiling is an effective way to create safe drinking water if you don’t have any supplies at hand.   

Solar Still To Purify Water

Solar Still

Building a solar still is an excellent method if you’re somewhere dry, such as a desert. They also work well on a boat. Aside from purifying the water, a still collects it, too.

To build a solar still, you’ll need a plastic tarp or a clear rain poncho. You’ll also need a container to hold the water. The container doesn’t need to be fireproof so that you can use one made of plastic.

If you don’t have any type of container, you’ll need to make one from leaves, bark, or other natural elements.

Making a solar still is a fairly simple process.

1. Dig a hole in the ground. It should be approximately three feet deep and four feet across.

2. Dig a second hole inside the first. It holds your water container.

3. You can collect water using plastic tubing. Run the tube from the container to the outside of the pit. You might need to use a piece of tape to help secure the tube in the container.

4. Cover the inside of the pit with leaves, but make sure they don’t block the container. Adding leaves helps increase moisture formation.

5. Place the plastic sheet across the pit. It should fit across the top without touching the bottom. Use rocks to help hold it in place.

6. Place small rocks in the center of the sheet. They should sit just above the water container. Add enough weight so that the sides of the tarp slope down at a 45-degree angle.

7. Add dirt and more rocks to the outside of the tarp. You want as tight of a seal as possible, which helps increase moisture buildup.

8. If you used tubing, tie or plug it closed.

Don’t lift the sheet for at least 24 hours. Results vary, but solar stills typically collect anywhere from a few hundred milliliters to a liter of water within about 24 hours.

The larger the still, the more water collected.

Build a DIY Filter To Purify Water

You can build a makeshift water filter with various items found in nature, such as grass and sand. You create a tower with different layers of materials. The water passes through each layer, which removes impurities.

To make a DIY filter, you’ll need three sticks of equal length.

Arrange them in a pyramid shape, then tie them together at the top. Next, place a container on the ground underneath the filter.

Next, hang several layers of textile cloth from the sticks. They’ll look like pouches. In each piece of cloth, put a different element, with looser elements on top of heavier ones.

For example, from the top down, here’s a common way to arrange a DIY filter:

  • Grass
  • Sand
  • Charcoal

The charcoal is the most important element and must be in every type of DIY filter. It does the heavy lifting by absorbing viruses, bacteria, protozoa, and other potentially harmful matter. The other elements, such as sand and grass, mainly filter out dirt, rocks, bugs, and other large bits.

Charcoal is easier to find than you might think. Burnt firewood turns into charcoal. In a survival situation, you’ll already need to build a fire. Use the charred wood from your fire pit to create clean drinking water.

Bonus: Alternate DIY Filter (video)

Instead of hanging cloth from sticks, you can also make a DIY filter using a plastic bottle. Cut the bottom off the bottle and then turn it upside down.

Pack it with the same materials described above, with charcoal at the bottom (where the cap would go if you were using the bottle normally). Then, add sand and grass until the bottle is about three-quarters full of material.

Pour water into the cut opening. It’ll drain through the layers of material and emerge from the mouth of the bottle. While this method is easy and effective, it’s also slow because you can only filter a relatively small amount of water at one time.

Use Bleach To Purify Water

Use Bleach

Although it sounds unbelievable, you can use bleach to purify water. It kills disease-causing organisms, but not chemical contaminants.

The bleach method usually works best for purifying water in an urban environment. After all, you probably won’t carry bleach with you on a hike, but you can easily store a bottle in your house in case disaster strikes your local water supply.

Only use unscented bleach with either 6% or 8.25% of sodium hypochlorite. Make sure the bleach has no added cleaners.

You’ll need a standard dropper. For every quart of water, you want to purify, add two drops of bleach. If the water is cold, cloudy, or colored, double the amount of bleach added. After adding bleach, let the water stand for about 30 minutes.

After the bleach purification process, the water will have a slightly chlorinated smell and taste but is safe to drink.

However, if the chlorine taste is too overwhelming, pour the water into a different container and let it stand for about two hours.

Ground Filter To Purify Water

A ground filter is essentially a well you dig next to a water source. Once dug, the soil naturally filters out many of the contaminants.

First, you’ll need to find a water source, such as a pond or a creek. Then, dig a hole about two feet away from the water. After that, you’ll need to dig deep, likely several feet or more. The deeper you dig, the cleaner the water.

Building a ground filter takes a lot of time and effort.

It’s mainly used in true emergencies when you have no other options for creating drinkable water.

Final Thoughts

In an emergency, one of the first actions you need to take is finding a source of drinkable water.

Fortunately, even if you have no supplies, collection and purification options are available.

If you have a source of water, you can boil it, add bleach, or run it through a DIY filter. If you’re in a dry area, you can collect water by making a solar still.

Finally, if you have no other options, you can create a ground filter by digging near a body of water.

Understanding how to purify water will help keep you hydrated, healthy, and safe in any survival scenario!

Greg - Prepping Insider

Hey, I'm a prepping enthusiast. Prepping for me is simply something of a passion. I have personally lived in many different rural properties that have given me a wealth of knoweldge and experience in practically living out survival and preparation situations. It’s not about getting the latest survival gadgets or buckets of food as its more of a lifestyle.

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