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How to Purify Water in an Emergency or Disaster Situation

CWanamaker is an engineer, thinker, and philosopher ready to explore all facets of life.

Would you drink this water?

Would you drink this water?

Emergency Water Treatment

Imagine that a disaster has occurred and access to cheap, clean, and uncontaminated water was suddenly interrupted. How would you ensure that you had an ample supply of water to enable the survival of you and your family? Given the fact the an average human being can only survive about 3 days without water, would you know what to do?


This is probably the most common and effective method you can use to prepare water for drinking. Boiling will kill most types of microorganisms and is relatively easy to do. Boil the water for at least 1 minute (5 minutes is better) and allow it to cool in a covered/protected location. (Drinking water that’s too hot can dehydrate you more). Water can be boiled over a fire, a stove (if there is power or gas), a solar oven, or even a car engine. After the water is boiled it may have an unpleasant taste. To correct this, aerate the water by shaking it in a closed container or pouring back and forth from one container to another. Follow aeration by adding a pinch of salt to improve the flavor.

Chemical Purification

If boiling your water isn’t option, chemical purification may provide the disinfection that you need. There are a variety of off the shelf chemicals that you can use to make water much safer to drink:

Charcoal. Did you know that charcoal can be used to help purify your water? Yes, it's true! In fact, most filtration systems sold at retail stores actually contain a good deal of charcoal inside of them. Charcoal is a great purifying substance because it has the unique ability to absorb sediments and contaminants while also improving taste. Charcoal is also easy to find because it is created whenever you burn wood (like when you have to create a fire to survive).

The process to use charcoal to filter your water is fairly simple. All you will need is charcoal, something heavy to crush it up with, and a container to hold and strain your water. There are plenty of guides online which show how simple it is to create a charcoal filtration system by using some campfire remains and a 2-liter bottle. Also, keep in mind that it's always a good idea to boil your water after you've treated it with charcoal because some bacteria may still remain inside.

Chlorine. To make water safer to drink, you can add about 8 drops (1/8 teaspoon) of unscented chlorine bleach (5.25% chlorine concentration) to each gallon of raw water. If the bleach has a different concentration of chlorine in it, you will need to use a different amount of it to prepare your water. For 1% concentration bleach, use about 40 drops per gallon. For 8% concentration bleach, use about 4 drops per gallon. After adding the bleach, stir the mixture well and let the container rest for at least 30 minutes. Bleach will kill some, but not all of the microorganisms that cause diseases. If there is a strong chlorine odor afterward, you may need to aerate the water to remove the smell.

Chlorine tablets, which can be found in the camping supply section of your local big-box store, can be used to make water safe to drink. These tablets will have instructions on the packaging that will guide you to properly prepare your water for use.

Calcium Hypochlorite: Granular calcium hypochlorite (bleaching powder) can also be used to disinfect water. You can obtain this chemical from a pool supplier or the pool section of your local big-box store. To prepare the water for drinking, dissolve ½ teaspoon of the high-strength powder in 1 gallon of water. Stir the mixture well and allow it to sit for at least 30 minutes before drinking. If there is a strong chlorine odor afterward, you may need to aerate the water to remove the smell.

Iodine: Tincture of Iodine (2% concentration) can also be used to disinfect water. This chemical is sometimes available in first aid kits. Add about 20 drops of this substance (40 drops for cloudy water) to 1 gallon of raw water. Stir the mixture well and allow it to sit for at least 30 minutes before drinking.

Iodine tablets may be available in the camping supply section of your local big-box store as well. These tablets will have instructions on the packaging that will guide you to properly prepare your water for use. If there is no instructions available, use one tablet for every quart of water you need to treat.

Stabilized Oxygen: There is some evidence to suggest that a “stabilized oxygen solution” can provide antibacterial properties when added to water. There isn’t much knowledge or research about this product as of yet, so this should be used as a last resort. In fact, there are many sensational or controversial reports about this product on the internet. Some websites have even made the claim that stabilized oxygen can cure diseases such as skin cancer. Stabilized oxygen can be found at most health food and nutrition supply stores.

The UV-A radiation from the sun can kill bacteria and make water safe to drink.

The UV-A radiation from the sun can kill bacteria and make water safe to drink.

Solar Water Disinfection (SODIS)

The SODIS method is one of the easiest methods you can use to purify water. It is so easy in fact that there are many organizations that are attempting to teach this method to people who are in danger of succumbing to water-borne illnesses. Essentially all you need to clean your water using this method is the sun, a transparent PET plastic bottle (most plastic beverage bottles are made out of PET, just check the bottom of the container), and about 6 hours of your time. Simply fill the PET bottle with water and let it sit in the sun for about 6 hours. The sun's UV-A radiation will penetrate the bottle and destroy the bacteria and parasites in it. The SODIS method can even be used in cold climates! If you need more information, check out the SODIS website.

Solar Distillation

A fourth option that you have to create clean, disease-free water is to make use of the sun's energy by building a solar still. This method requires lots of time and sunshine to get any appreciable amount of water. Another downside to this method is that the water will be devoid of any minerals or flavor. Salting and aerating the purified water can help with this.

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To build a solar still, you will need a sheet of clear plastic and at least 2 open containers to hold water. Fill one container with the dirty water and place it under the plastic sheet. Place the clean and empty container under the plastic sheet as well. Stretch the plastic taught over both of the containers. Use a rock or another object to create a depression on the plastic sheet just above the clean water container. As the sun shines through the plastic, it will heat the dirty water causing it to evaporate. Water vapor will condense on the underside of the plastic sheet and begin dripping into the clean container. If you have plastic tubing available, you should consider connecting it to the clean water container so you won't disturb the system when you need a drink.

Clarifying Water First

If the only water available to you is cloudy or laden with sediments, you should make an attempt to clarify it prior to disinfection. This can be accomplished by either straining the water through several layers of fabrics, such as clothing, or allowing the solids to settle out.

An example of a solar still.

An example of a solar still.

Bio-Sand Filtration

Surprisingly, one of the easiest ways to purify water is to use the sand and silt that makes up the Earth's surface all around us. It's a known fact that water that is pumped out of the ground is often free of contaminants because it has been naturally strained through the pores of sands and silts. With one of Earth's most basic natural processes in mind, one can easily create a devise that mimics nature and purifies water using only sand and silts.

To build a basic bio-sand filter you will need a couple of items: 1) a tall container,2) a hose or drain tube, and 3) a variety of clean sands, silts, and gravels. First connect the hose to the bottom of the container by boring a hole in the side of it. Next, fill the container first with a few inches of gravel then by a few more inches of sand. Next filled 2/3 of the remaining container volume with very fine sand and silt. Finally, fill the remainder of the container with regular sand and gravel. Some biosand filters also incorporate a layer of charcoal inside. If you have some available I would recommend including it in your filter design.

To use your new bio-sand filter, simply pour your dirty water into the container and let it slowly filter through the container and in then out the hose.

I have include a few links to more detailed guides on how bio-sand filters work and how they can be easily constructed in an emergency situation:

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2011 Christopher Wanamaker


Christopher Wanamaker (author) from Arizona on October 21, 2014:

Daniella Lopez - I actually haven't heard of the use of charcoal before but that actually makes sense. Activated charcoal is actually quite good at absorbing contaminants - im going to do some reaserch and perhaps ill update this article. Thanks for your input!

Daniella Lopez on October 21, 2014:

Quite the informative hub you have here. I have also heard that activated charcoal can be used to purify water. I had never heard of using iodine, though. Thanks for sharing!

Angela Chamberlain- from Vermont on November 05, 2012:

Very interesting! Thanks for the education!

Christopher Wanamaker (author) from Arizona on November 03, 2012:

The idea that PET bottles "leach" chemicals when heated is not based on any science, and is unsubstantiated by any credible evidence. This allegation has been perpetuated by emails until it has become an urban legend, but it just isn't so. Here are several sources pointing to this fact:

International Life Sciences Institute:

International Bottled Water Association:

Practical Gastroenterology:

Danika Carter on November 03, 2012:

Polyethylene terephthalate (PET) bottles leach several hormone disruptors including phthalates and antimony and other dangerous chemicals when heated, so I would not consider a plastic bottle a safe way to purify water at all. You're just trading one danger for another.

shivani rana on June 12, 2012:

it give us very useful information............don't u think guys

rochelj from USA on November 11, 2011:

Water is such as basic necessity, it is important to know how to purify it in case of an emergency. this is very useful info that you are sharing. thank you!

Christopher Wanamaker (author) from Arizona on October 24, 2011:

Molometer- Thanks for reading. I am thinking about adding some more tips to this hub in the near future.

Micheal from United Kingdom on October 24, 2011:

What a really useful and informative hub.

Bookmarked and voted up and interesting.

We never know what is around the next corner and this info could be lifesaving. Well done.

Christopher Wanamaker (author) from Arizona on June 12, 2011:

Thanks fellow Hubbers! Clorox probably removed it because of liability reasons, but I can't confirm that.

WillStarr from Phoenix, Arizona on June 12, 2011:

Great Hub, and one to bookmark. Clorox bleach once had water purification instructions right on the bottle, but it's no longer there for some reason.

Up and very useful!

Pamela Oglesby from Sunny Florida on June 12, 2011:

This is a very informative hub. Since I live in an area that can be vulnerable to hurricanes I think this is good information to know. Rated up and useful.

Stephanie Henkel from USA on June 03, 2011:

Most of us in the U.S. take for granted that we will have access to clean, safe drinking water, but we never know when disaster might strike. You hub is very useful in reminding us how to purify our water. I found the solar still instructions especially helpful as I never knew how this was done. Thanks for a nice hub!

JP Carlos from Quezon CIty, Phlippines on June 03, 2011:

This hub brings back memories from my camping and survival training days. Just to add some info, do take into consideration your altitude when boiling water. At higher altitudes, water boils at a lower temperature. You need to boil it longer.

Solar distillers are slow but it's better than nothing. Just make sure your plastic sheet is as clean as possible.

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