by Cody Lundin
The membranes in all filters and purifiers will eventually clog and need cleaning or replacement. Because of this, it's wise to have an extra one around the house. Most replacement filters are not cheap, but the quality of the filter should be why you purchased the unit in the first place—not for how pretty it looks in the kitchen. The life of the membrane can be increased dramatically if nonpotable water is carefully filtered beforehand or at least allowed to settle, thereby eliminating all visible signs of particulate matter. If you're going to invest in a costly home-based water filter or purifier, you want it to concentrate on screening out harmful pathogens, chemicals, pollutants, and heavy metals, not the pond scum you were too lazy to screen out beforehand.
Hopeful Homemade Filters?
A few high-buck water filters claim to screen out almost anything undesirable. Some with reusable filters even claim to screen out radioactive radiation, but how to clean the radiation out of the filter remains a mystery. As with all things self-reliant, it's your job to research which water filter or purifier is best for your family. Don't buy cheap crap, but at the same time take a careful, skeptical look at what manufacturers claim, even with the successful independent test data that a few have.
Military survival books and others usually include a homemade water filter that can be made with improvised items in the field. I have seen illustrations using the leg(s) from a pair of pants, or two containers filled with various makeshift filtering materials. Some of these materials, such as carbon from a fire and sand, have been used for thousands of years for the same purpose.
So let's say you tie off the bottom of one or both legs of a pair of pants. Then you hang the pants and fill the void within the legs with layers of carbon, sand, and maybe polyester quilting, such as from a mattress pad. You pour water into the top of the pants and let it slowly gravity filter through the layered materials to drip into a waiting clean container below. Now what? Is the water safe to drink? Is it free from toxic chemicals, nitrates, pesticides, pollutants, and garbage that the other water disinfection methods won't eliminate? How can you visibly know for sure when dealing with contaminants that are invisible to the naked eye? When will the damp and dark filter material start to breed weird microorganisms that will then find their way into your filtered water?
I don't know anyone who has used any improvised filtering method who has had the resulting filtered water tested for the effectiveness of its methodology. Even if it were effective, there is no guarantee that the results would be identical the next time due to tremendous variables. If your family has no other option, by all means, improvise whatever you can to make your water safer to drink. But don't exclusively rely on the sketchy methods presented in many survival books for the safety of your family—especially when you have a choice!
Boiling
Boiling is hands down the oldest means of disinfecting water. You'll need a container, the water in question, and a heat source. Although almost any fireproof container will work for conventional boiling, it helps to have a container that's suited for the job. A great multiple-use pot is two to four quarts in capacity, stainless steel, with a tight-fitting lid and bail (handle). I can't say enough about this simple yet masterful piece of gear. You can use it for many things: melting snow or ice for water, cooking dinner, making coffee, storing other survival gear, digging, etc. The next time you see a cable channel show documenting rare indigenous peoples hidden away in some remote jungle, check out what they have for "white man" gear. As the camera pans over the village, you'll probably spy steel machetes and a metal pot or two, traded for God knows what. The natives are masters of their environment and can make fire from sticks and rope from plants, but ahh, that steel edge and that shiny thing that can be put straight onto the fire without burning up. . .wow, now that's worth having. Are you laughing yet? Then try leaving all of your metal containers behind on your next camping trip—without bringing your prepackaged fancy camping food. Metal containers have truly revolutionized the world, just one reason why they appear on my "Really Cool, Gotta Have It, Multiple-Use Stuff" list in a future chapter.
The tight-fitting lid, or some improvised lid if one is not available, will save you fuel (as the water will boil quicker) and water (that would be lost through evaporation), both time-precious commodities. The bail or handle allows you to easily carry the pot or hang it from a branch or wire for improvised backyard or back alley business. Stainless steel is tough and safe to use long term for water or foods without the potential health risk of aluminum.
There's a lot of bogus garbage on the Internet and in books about how long to boil your water to make it safe to drink. Heat works exponentially over time to kill pathogens. Dairy farms don't boil milk, they pasteurize it. South of the border in Mexico, if you're unfortunate enough to get stuck drinking tap water, people in the know recommend that you at least drink water from the hot side of the faucet, after letting it cool down, of course. At sea level, water boils at 212 degrees F (100 degrees C). Even if you only have enough heat to get your water up to 180 degrees F (82 degrees C), spend the several minutes it takes to let it cool down, especially with a lid on the pot, and the heat will still kill all harmful pathogens. Armed with this knowledge, you can better understand why I'm not recommending that you boil the hell out of your water for a half an hour or more. I explain more about the pasteurization process after this segment.
Disinfecting Water by Boiling
To disinfect your water by boiling, fill the pot with water and put the lid on. If you don't have a lid, improvise something such as setting another pot on top. Put the pot over your heat source and simply bring it to a boil. This action alone will kill all pathogens, as some species die as the water is being heated up. If you live at elevation, or are dealing with truly sketchy water, let the water boil for a minute or two. When water boils, the level of oxygen dissolved in the water decreases, making it taste "flat." After the water cools, its taste can be improved by aerating it by pouring it back and forth between two clean containers or shaking it vigorously in a closed container with air space.
After the water has boiled, turn off your heat source or take the pot off the fire and leave the lid on until it cools. Again, this continued "free heat" further guarantees that all nasty critters will die. When I hardboil eggs, I bring the water to a boil using another pot for a lid, shut of the heat, and let the eggs cook for several minutes in the scalding water. Over time, this saves a lot of fuel while achieving the same results. While some of you might be wondering when I'll get a life, harboring a conservation mind-set now will make the transition over to an emergency scenario with limited supplies that much easier and less scary. You'll also do the Earth a favor, and save money so you can work less at the job you hate. After the water has cooled sufficiently to drink, you're ready to hydrate. You can use nonpotable water for cooking as well when bringing any food source to a boil. There is no need to boil water, making it safe to drink, and then reboiling it again for eight minutes when cooking the survival pasta.
While boiling destroys the waterborne pathogens that we're concerned about, it takes effort to continually boil water for drinking, especially if all you have are smaller containers. For those living in hot climates, with no air conditioning because the grid collapsed, the last thing you will want to do is boil water. This procrastination will lead to further dehydration. Boiling requires a heat source, and heat sources need fuel to burn. Fuel—whether it's white gas, propane, or the busted-up kitchen table—might be hard to come by. The heat produced from burning fuel can also burn down your house, garage, or town without proper care as to where the heat source is created and managed, and having the know-how and tools to properly extinguish a blaze if things get out of control. In other words, boiling to disinfect water takes a lot of energy and responsibility, so the "drop, drop, fizz, fizz" convenience of the before-mentioned halogens should be a viable option for every household.
Pasteurization
Contrary to poplar belief, it is not necessary to bo
il microbiologically contaminated water to make it safe to drink. I wrote about boiling because it does work, and may be more valid than other disinfection methods under certain circumstances. Also, some of you may feel super-paranoid about trusting the pasteurization process (if you're a milk drinker, get over it). Also, contrary to what many people believe, it is usually not necessary to distill water to make it safe to drink. I cover distillation next, as many of the water disinfection methods outlined herein, including pasteurization, will not help if water is brackish or chemically contaminated.
While sterilization kills all of the organisms in the water, pasteurization kills only those organisms that cause harm to humans. Pasteurization involves heating water to 149 degrees F (65 degrees C) for six to twenty minutes, or to a higher temperature for a shorter time. (Note: There was some contradiction in my research into how long the water being pasteurized must remain at the peak temperature of 149 degrees F. Whichever time you decide to use, six or twenty minutes, remember that you will not be swilling down water at that temperature anyway and that the water will continue to disinfect as it cools to a manageable drinking temperature.) Pasteurization kills all bacteria, viruses, and parasites, such as Giardia, cryptosporidium, endameba, the eggs of worms, shigella, cholera, salmonella bacteria and those that cause typhoid, the enterotoxogenic strains of E. Coli, Hepatitis A, and rotavirus, to name a few.
A standard glass thermometer can be used to accurately measure when the correct temperature for pasteurization is achieved, as will another device available from many solar cooking businesses online or elsewhere. This option is the Water Pasteurization Indicator (WAPI). A prototype was first developed in 1988 by Dr. Fred Barrett, who worked for the U.S. Department of Agriculture. The present WAPI device was developed by Dale Andreatta and other graduate engineering students at the University of California at Berkeley. The device itself consists of a polycarbonate tube that's sealed at both ends. The inside of the tube is partially filled with a blue soybean fat that melts at 156 degrees F (69 degrees C). To use, the WAPI is placed inside the water container being treated with the fat end up. It's easy to tell when the water reaches 156 degrees F because the highly visible fat melts and runs to the bottom of the tube. The WAPI is durable and can be used many times, and can be placed in a solar oven, cook pot, or over a stove or fire. Heating water to the pasteurization temperature rather than the boiling point can reduce the energy required by up to 50 percent, saving fuel, time, and water.
Distillation
While the above-mentioned water disinfection techniques work well at killing organic waterborne pathogens, they will do nothing to remove other potential containments from water such as heavy metals, salts, and chemicals. Distillation requires boiling water for many minutes and catching the resulting steam. The Seri Indians in northern Mexico desalinate seawater by boiling it in fifty-five-gallon drums. They wrap a wet, cool rag around a copper pipe exiting the container, which cools down the escaping steam that is then caught in a waiting container. This method is extremely fuel intensive, yet dying of dehydration trumps deforestation. Although tedious and a fuel hog, distillation gives survivors a much better chance of removing suspected dangerous contaminants from gathered water.
For small-scale water distillation, fill the largest cook pot you have halfway with nondisinfected water. As the water will need to be boiled for several minutes, there is no need to disinfect it beforehand. This cook pot should have a lid or one that's improvised that will conform to the following directions. The lid will be put on the pot upside down to allow for its resulting convexity to direct trapped steam, as it cools and turns to water droplets, toward the center of the lid. Before putting on the upside down lid, attach a smaller, heat-resistant container such as a cup or bowl to the lid's handle using wire or string so that it hangs right side up inside the pot without touching the water. This cup or bowl catches the directed water droplets from the lid. Boil the water for as many minutes as required to fill the attached cup or bowl. The resulting water that drips from the lid into the cup or bowl is distilled and should be free from waterborne pathogens and other contaminants. Although making a water distiller may be a pain in the butt, once it's made, it can be used many times. Water can also be distilled after being disinfected by other methods for those who are dealing with extremely nasty water or who simply want added protection.
The SODIS Water Treatment Method:
Using Free Ultraviolet Radiation from the Sun
In 1991, research for the future SODIS water treatment method was undertaken by SANDEC (the Department of Water and Sanitation) at the EAWAG (Swiss Federal Institute for Aquatic Science and Research). They conducted wide-ranging laboratory and field tests to develop and refine for general use the Solar Water Disinfection Process (SODIS). Their extensive testing revealed what some of us desert rats have suspected for years, that the ultraviolet radiation from intense sunlight shining through a nonopaque container filled with nonpotable water will irradiate and kill undesirable waterborne pathogens, rendering the water safe to drink. In truth, the inspiration for using radiation from the sun to kill pathogens in nonpotable water started to develop in India as long ago as 2000 BC.
For the past decade, SANDEC has been providing information, technical data, and advice to local institutions and more than twenty developing countries worldwide. Currently, the SODIS method is used to treat the daily drinking water of more than two million people around the world. Studies into the effectiveness of the SODIS program have shown a reduction in dysentery by 20 to 50 percent. For developing nations, further benefits were achieved by combining SODIS with hand-washing programs.
You as a reader are aware by now that many hundreds of thousands of people die each year in developing counties from dysentery and disease caused directly or indirectly from contaminated water. My hat goes off to the people at SANDEC and EAWAG and many other organizations for their work in solar water disinfection; they are spending time and money to truly make a difference in our world, a difference that can be owned and operated by the people themselves, not corporations.
SODIS does not completely sterilize water of all critters, as it's primarily used to inactivate the pathogenic microorganisms that predominantly cause diarrhea. When the SODIS bottle is exposed to the sun, other harmless bacteria present in the water may keep growing. The SODIS method does not produce sterile water, as drinking water does not have to be sterile. Laboratory research has shown that many bacteria, viruses, and protozoa are eliminated including, but not limited to, the bacteria Escherichia coli (E.coli), Vibrio cholerae, Streptococcus faecalis, Pseudomonas aerugenosa, Shigella flexneri, Salmonella typhii, Salmonella enteriditis, and Salmonella paratyphi; the viruses bacteriophage f2, rotavirus, and encephalomyocarditis virus; the protozoas Giardia spp., and Cryptosporidium spp.; and the yeasts and molds Aspergillus niger, Aspergillus flavus, Candida, and Geotrichum.
In a nutshell, the SODIS method involves filling up a clear, plastic, one- to two-quart container with nonpotable water. This bottle is then put into direct sunlight, on the roof of a house or elsewhere, for several hours until the ultraviolet radiation from the sunlight disinfects the water for drinking. While there are several specifics to the methodology to ensure success, and I write about them below, this data can also be found on the SODIS Web site at www.sodis.ch/.
Finding and Using Containers Compatible with the SODIS Method
Concentrated sunlight (ultraviolet radiation) is the name of the game so stay away from containers with more than a one- or two-quart (or liter) capacity. Don't use large containers!
Ultraviolet radiation is reduced by increasing water depth. The more surface area-to-volume ratio you can achieve, in other words, the more of the sun's rays that can shine through the smallest "thickness" of water, the better the method will work. Although clear soda bottles are not optimal for the SODIS method as they have a small area for exposure to sunlight, they are common and readily available in most towns and cities. (See comments o
n using plastic bags below.)
Use only newer, clean, clear plastic containers with lids. These containers should be in good shape, not old, dinged, and scratched up ones that will block UV radiation. In like manner, opaque, tinted or colored plastics will block the necessary radiation from the sun and should not be used for SODIS. Older clear containers and colored plastics can be utilized, if clean, to store water that has already been treated in the newer clear bottles. All plastics break down and age when exposed to the sun, thereby reducing their transparency for maximum UV radiation. This breakdown transforms plastic materials into photoproducts. SODIS laboratory and field tests showed that the resulting photoproducts were generated only at the outer surface of the bottles. No photoproducts or additives (UV-stabilisators) were observed leaching into the water itself. For the length of most urban disasters, sun-weakened bottles won't be a problem, as the SODIS people recommend that you retire all containers used for SODIS after one year of continuous daily use.
Research carried out in Canada at Montreal's Brace Research Institute (BRI), in collaboration with international colleagues, found that plastic bags are the best material for solar water disinfection. Heavy-duty freezer bags, as mentioned, will hold either a quart or a gallon of water sealed and will lie flat in comparison to soda bottles when full, thus exposing more water to greater concentrations of UV radiation. While this departs from the SODIS method of plastic bottles, plastic bags, although far less durable, may be a viable option for you. Any labeling printed on the bag should be turned down so as not to impede solar radiation. Be careful of hot, conductive surfaces as they may deform and melt the bags.
A note about glass: While clear glass bottles can be used, glass is thicker than plastic and will block some of the UV radiation and add time for the water to heat up. Glass containers are also heavier when empty and can be easily broken. Tests done with improvised large containers made with window glass did not work, as the glass did not transmit enough UV radiation. Many windows on the market have UV inhibitors to keep your couch and chairs from fading in the sun.
