How to Clean Untreated Water

Written by Brandon Garrett

While it is difficult to determine which item is most essential in a survival situation, you could certainly make a strong case for clean water. Water is used for numerous activities that can quickly become your top priority in survival situations like cooking, cleaning, sanitation and drinking. Because water seems so easy to get before a disaster, you don’t fully understand how much you rely on it until you find yourself without water or rationing your supply.

In the past we’ve written about how to store water correctly and the need for rotating stored water frequently. Today, we want to take it a step back and discuss in detail the threat of untreated water and what you can do to make sure you and your family will have plenty of clean, treated water in a survival situation.

What Is In Untreated Water?
To get a good idea of what might be inside your untreated water, trace the origin of the water back to its source.

Rainwater picks up whatever is in the air as it falls, including dirt and acid. Surface water, like rivers and lakes, can contain algae, sediment and silt. If your water comes from a public supply like a well, it is possible that water could contain micro pests that thrive in areas with little sunlight and lack aeration. Water found near agriculture or urban developments can contain pesticides, herbicides and other pollutants that negatively affect water. And even water that is improperly stored directly on cement can attract toxins found in the cement.

The real threat hiding inside untreated water are these micro-organisms: Bacteria, protozoa and viruses.

Examples of bacteria strains found in water include E. coli, salmonella, Campylobacter jejuni and many others. Some of the more harmful protozoa that thrive in water include Giardia lamblia and Cryptosporidium paravum, parasites that can survive for weeks in cold water. And viruses like Hepatitis A and rotavirus sometimes take up to 4 hours in a chemical treatment to be eradicated.
Water that comes out of your tap has been treated, and thoroughly. Unless you hear otherwise from your local community water system, it is safe to assume your tap water is safe to use for drinking, cooking and any other activity. For more information on your tap water, consult this booklet “Water On Tap: What You Need To Know,” from the EPA.

What Happens If I Drink Untreated Water?
The impact of ingesting untreated water at the less intense end of the spectrum starts with diarrhea or other prolonged intestinal discomfort. From there it can progress to vomiting, rashes, muscles aches, fever, chills and more serious impacts like neurological symptoms and jaundice. Depending on what kind of microorganism was in your water, the worst case scenarios result in contracting illnesses like botulism, cholera, dysentery and in rare cases death. We strongly advise you not to drink untreated water.

What Water Treatment Options Do I Have?
There are three main options for treating water: filters, chemicals and boiling. In this section we’ll discuss the pros and cons of each option.

Filters. This option is considered by many to be the easiest and safest way to treat water for drinking. Portable filters work by separating the microscopic critters that live in water from the actual water. Filters don’t kill these creatures, but instead trap them and keep you from ingesting them. A water filter’s effectiveness in catching these pathogens is determined by its pore-size efficiency. This is the measurement that describes the size of the microscopic openings in the water filter. The standard measurement of pore-size efficiency is called a micron, which to give you a reference point is 1/1,000 of a millimeter. As you look for a water filter for your emergency kit, make sure the micron size is at least less than 0.4 microns, as this is the threshold for removing bacteria from water. Protozoa and and parasites are much larger than bacteria, and can be removed from water with a filter of nearly any size.

Chemicals Of the three main water treatment options, this option is used most often by those storing large amounts of water. These chemical treatments kill the bacteria and viruses living in the water. These treatments have been approved and certified by the EPA for human consumption, as opposed to chemical solutions made for cleaning. Two popular chemical treatments are iodine and chlorinate. Iodine, while lightweight and easily transportable, leaves a trace taste of iodine in the water, which affects the flavor of the water in a way that many find unpleasant. Because a small amount of chlorinate can purify a large amount of water, it is the treatment of choice for large stores of water.

Boiling This option is an old standby, but tends to have more drawbacks than advantages. For starters it requires a good deal of fuel to heat water to its boiling point, which can be a precious resource in a survival situation. Secondly, boiled water can have a flat taste, which comes from the loss of oxygen in the water while it is boiling. And finally, the temperature of boiled water can present a problem if you need it right away, but can’t use hot water. If you are boiling your water to purify it, boil it continuously for at least 5 minutes and then transfer it back and forth from one container to another to aerate the water.

Need for Water
The Federal Emergency Management Agency has long suggested that storing one gallon of water per day per person is the minimum recommendation in an emergency supply kit. While you calculate how much water you should be storing, it is important to take into account your local climate, pets and the health of those who will rely on your water. And finally, you should know how much water you’ll need to prepare the food in your emergency supplies, as different types of food require varying amounts of water. If you are still unsure of how much water you’ll need, consult our ultimate water storage guide.

Updated September 7, 2013


  1. Lauralee Hensley wrote:

    I think FEMA estimates too low on water needs. That’s maybe enough to stay hydrated, but what if there is no air conditioning and the weather is very hot. You’ll need more than one gallon to stay properly hydrated. Then if no air conditioning wouldn’t you like to hang up damp sheets over a curtain rod with a breeze blowing into your home? The evaporation from the curtains can help to cool down a bit dry hot air, yet kind of useless unless there is a breeze blowing in toward the direction of the damp sheets. Then what is you want to sponge off or wash your hair? Then what if you want to wash a cooking pot and utensils? Then you need water to hydrate emergency prepardedness foods if freeze dried or dehydrated.

    September 9th, 2013 at 3:04 pm
  2. Jason wrote:

    Well one thing a lot of people don,t think about buying is paper plates paper cups n plastic utensils before a storm get costco
    Size. Plus you should freeze some gallons to help keep food colder longer also use freezer ziplock bags. Those make great sleeves to fit in coolers. When that melts u have more clean drinking water if they r not damaged. Don’t forget pilgrims used to add alcohol to almost everything they drank to fight disentary(not sure spelling) and kill other virus bacteria parasites. Of course they burned people at the stake bc they thought they had magic powers. But still works n alcohol can be used for lots of things. I wished they sold something that can heat water so you can give kids a warm bath like handwarmers u can drop in the water. You can always build a still to purify water n make irish potato juice(vodka).i m irish. Potatoes are the easiest thing to grow. That’s why Vikings n Celts main crop, grow year round. I also installed a main filter before goes to rest of the house. That thing gets nasty looking.

    September 12th, 2013 at 6:29 pm
  3. Diana wrote:

    The Vikings main crop was potatoes? Sorry, Jason, I’m afraid not. The potato is a South American plant that didn’t reach Europe until the late 1500s and didn’t become popular there until the late 1700s–after which the Irish did, indeed, grow a lot of them (hence the terrible effects of the potato blight there in the mid 1800s), as did many other people. The Incas depended heavily on potatoes. The Vikings, though, would have depended on oats, barley, and to a lesser extent rye, the grain crops that can handle short, cold growing seasons. They brewed beer from barley rather than distilling vodka from potatoes. (Not that I don’t agree with you that ethyl alcohol is an incredibly useful item for food storage. Try storing sliced ginger and garlic and similar perishable ingredients in high-proof alcohol–works better and is much safer than storing in oil, and the booze evaporates as soon as it hits a hot pan.)

    As for low-water-use washing up–that’s why the goddess gave us sand, the mainstay “dish powder” on desert treks. When water is precious, you do your scouring with dirt and sand. Dirt absorbs all damp and oily residues, and sand will scour off even the worst burnt-on crud. Then you can do a quick rinse/wipe with a very little water if you’ve got a bit to spare. :)

    I’d save my disposables money to stock some disposable biodegradable towels/washcloths and a couple of sets of disposable sheets (they sell them to the hospitality industry) to minimize the water needed to maintain my usual standards of personal hygiene during a prolonged emergency (plus some no-water/no-rinse body cleanser and shampoo) rather than piling up mounds of grubby used and unwashed plastic utensils and food-soaked paper plates and cups to attract vermin.

    With a hand-crank washer that can wash and rinse a couple of complete sets of clothes using less than 5 gallons of water (especially if you use a saponin rather than soap or detergent for the surfactant) plus a composting toilet, you will have most of your stored water available for drinking and cooking, but still won’t have to worry about stench filling the air around you or your homestead or insects/rodents following their noses to your place.

    September 17th, 2013 at 4:13 am
  4. REID wrote:

    It’s also wise to lok into making a Solar water purifier. Using 2 liter soda bottles and slanted rauck with reflective backing to keep them oriented toward the most direct sunlight. Also having your own well is great insurance. you can Drill your own . Look at Deep Rock manufacturing for DIY well drilling outfit . Throw in with several friends , buy one outfit and everybody gets a well. A drilled well is a easier safer way to supply water. How people used to dig a well is beyond me . it’s really hard dangerous work and since a hand dug well is usually in the realm of 25-30 ft deep it is easier for them to become contaminated and then again there’s that back breaking dangerous work .

    September 17th, 2013 at 4:38 am
  5. Reid wrote:

    look at the Deep Rock website: www(dot)deeprock(dot)Com.
    Also Northertool(dot)com has an in-hole solar powered electric well pump suited for a 4″ well several hundred feet deep. and of course there manual well buckets . If you have land you could drill more than one well and then cap them off awaiting the time the need arises for their use.

    September 17th, 2013 at 4:57 am
  6. REID wrote:

    look at the Shur-flo in-hole solar well pump, 24v, 4.6 amp. 4″, 230Ft head, 82 gallon / per hour, Item # 9325-043-101, Northern Tool, Norther tool(dot)Com

    September 17th, 2013 at 5:07 am
  7. Jason wrote:

    Incas grew and still tribal areas in that area main stable is yam or sweet. White we’re around for around a lot longer. Vikings and celts would grow them in bushels of hay bc you can grow them year around. That is a fact. I never said they used it for alcohol just made a joke that you can. Viking more used honey to make a mead. Potatoes were around a lot longer then that you should look you medieval recipes.

    September 17th, 2013 at 8:24 am
  8. Jason wrote:

    2nd. People would much safer buying a supply for a large gathering of plastic n plates before a storm. Not only does it insure the objects are clean but they don’t take up much space and are good for which ever area you live in. I live near a swamp near coastal. Not using that dirt to be clean. Don’t forget how many different insect species live in the ground. If your land is covered in four feet of snow you don’t want to exert the energy to digging up the area to get dirt to clean. So before you knock some1 down maybe just make a helpful comment. The Romans have recipes with potatoes.

    September 17th, 2013 at 8:33 am
  9. Diana wrote:

    Jason, I wasn’t trying to put down your advice, just correct an historical error and add some other options.

    Sorry, but neither the Romans nor the Vikings ate potatoes. Really, they didn’t. The things were completely unknown in Europe until the 1500s. As to sweet versus white potatoes, both were and are grown and used in the Americas. The high mountains in Peru, however, are distinctly unsuited to the tropical sweet potato. There it was white (and even yellow and purple) potatoes. Peruvians still eat a lot of potatoes, and some of the best in the world (try a Peruvian criolla potato sometime if you can find one), and they also still eat their traditional “freeze-dried” potatoes made outdoors in the high cold and dry air of the Andes. Those can be a bit of an acquired taste due to both the potato variety and the production method, but are a remarkable example of “primitive” food storage technologies.

    September 19th, 2013 at 2:42 am
  10. NLJ wrote:

    After the BIG floods in Colorado these past weeks it really got me thinking about storing in place. Eek. Having a bag you can grab & carry is all that might work & the weight of it on your head might keep you from floating away in the water. Hmm

    September 19th, 2013 at 8:06 pm
  11. Diana wrote:

    There is no way to guarantee against everything, and it’s always possible food storage could end up either being destroyed or having to be left behind in a disaster. That’s why being prepared involves being prepared both to shelter in place for several weeks and to evacuate quickly with the necessities to cover you for 3 days.

    For those involved in the floods in Colorado, some did need to evacuate their homes quickly. OTOH, many others were stranded in place without any incoming food, water, or other aid for several days to more than a week. Many were told either not to try to evacuate because roads/bridges were gone, or that is was on their heads if they decided to try to do so because roads/bridges were unsafe. The residents of at least one whole county were specifically told they should shelter in place rather than try to reach alternate shelter on their own. I’m sure those towns that were completely cut off for days were grateful for anything and everything anyone in town had stored for an emergency. Even if some of it was washed away, whatever was left would have made a big difference. Also, anything in long-storage cans that didn’t wash all the way down the mountain could likely be rescued from the mud and still used after the can was rinsed off. What just happened in Colorado is overall a much better example of why you would want to be able to shelter in place than the contrary.

    September 20th, 2013 at 8:12 am
  12. NameDan Fuqua wrote:

    I love this kind of information. Here’s one that I think might be useful in many instances. We have a five gallon water storage bottle for non-potable use. If I don’t use something to control bacteria or algae, the water get sick very quickly. I use about One pint of 3% HYDROGEN PEROXIDE, that can be bought at most places for under 1.00. The water stays clean and bacteria free for the whole boating season even in hot climates! This is great to have on hand for cleaning and as an antiseptic. Check out the many uses for Hydrogen peroxide and tell me what you think! It also can be ingested in a diluted state if water needs decontaminated.

    October 24th, 2013 at 11:05 am
  13. DAbbott wrote:

    Wish the article would have mentioned silver. Also, this site used to sell some tablets that would not only disinfect water but would case solids to drop out so they could be filtered out through a cotton cloth.

    August 9th, 2014 at 5:30 am
  14. Fred Perez wrote:

    Sorry but the potato was first domesticated in the region of modern-day southern Peru and extreme northwestern Bolivia between 8000 and 5000 BC. The Spanish brought the potato to Europe. This can be easily verified online.

    August 9th, 2014 at 7:26 pm

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