(I originally had no intention of posting the second half of the water procurement chapter of the new book as an excerpt. I mean, basic marketing 101 says to give you enough of a taste that you want to purchase the book to see what else is out there. Nevertheless, given some of the comments and questions I had—and at least one was answered in this week’s Campfire Chats article, I decided that readers here deserved to have the whole story, on this crucial subject at least, because of your continuing contribution and loyalty. There’s a lot more to the book as well, obviously, with the food and shelter chapters alone more information packed than most “survival” books out there have in their entirety, anyway. So, the rest of the story, as old Paul used to say….) Water Filter Systems Whether labeled as a filter or a purifier, these Rude Goldberg contraptions share the same essential purpose: to clean up your drinking water. Despite this, there are significant, potentially important differences between the two, based on how they work. After having had published standards for water purifiers for decades, around 1998, the US EPA finally published standards guidelines for water filtration systems. Devices that pass the tests and meet these standards will have a product registration number clearly displayed, making it apparently easy to select a functional product. However, it’s important to understand the basics, in order to know what you’re actually getting. A filter works by passing water through the device, but trapping microorganisms and particles. The vital metric in these devices in pore size. Pore size can be stated in two ways: nominal or absolute. A nominal pore size is an average, meaning there are going to be pores both smaller and larger than the stated size. In other words, a nominal 5 micron pore size might actually have enough larger pores to allow Giardia to pass through. An absolute 5-micron filter though, will mean that no pore in the filter device is larger than 5 microns, which will be sufficient to trap and hold Giardia cysts. Many filter makers will claim that their products will meet two of the three standards set by the EPA for purifiers, but no mechanical filter device will offer a small enough pore size to remove viruses, which is the third part of that standard. As defined by the EPA, a water purifier is able to “remove, kill, or inactivate all types of disease-causing microorganisms from the water, including bacteria, viruses, and protozoa cysts.1” It must be verified to remove 99.9% of protozoa, 99.9999% of bacteria, and be able to inactivate 99.99% of viruses, which are simply too small to filter out2. In order to manage this, the typical purifier will combined a physical filter with chemical action: most have some sort of resin-based matrix that releases iodine to inactivate bacteria and viruses. Another common method is to use a bed of activated charcoal or silver-impregnated elements. Silver is utilized to inhibit bacteria growth in the filter itself, although the benefit to the water passing through is open to debate. Activated charcoal works by absorbing chemicals via the process of adsorption, meaning the molecules adhere to the carbon particles. This will remove pesticides, herbicides, chlorine, and iodine, and some studies suggest it will also remove heavy metals from the water. For this reason, activated charcoal is commonly available as part of the filter element, or as an add-on cartridge to the unit. Filters for backpacking are made of various materials. These include ceramic, activated charcoal/carbon, various fibers, and plastic mesh matrices, as well as combinations of these. Due to the small pore size needed to filter out protozoan cysts, the filter can tend to clog up very fast when plastered with algae, silt, or other larger pollutants. For this reason, many filters use metallic or fiber pre-filters to catch the coarser material where it can be more easily cleaned out. For filters that don’t feature these—or if the filter is insufficient for some reason—it is a simple and trusted method to strain water through a piece of fabric, ranging from a simple cotton bandanna or piece of a t-shirt, to using coffee filters. For simple filters, the filter element can typically be cleaned via scrubbing, rinsing, or backwashing with clean water. For those filters that offer activated charcoal purifiers built into the filter though, this component will require somewhat frequent replacement, because the charcoal absorbs the chemicals, bonding with them at the molecular level. If you have a filter that facilitates cleaning, it is essential that you not only know how to clean or replace the element, but that you have the means to do so. The rightly famous Sawyer Mini filters, for example, come packaged with a medium sized syringe that is specifically there for backwashing the filter device with clean water to push out any residual crud that has built up with use. I’ve seen a large number of people though, including some self-professed experts on social media, who simply discard that syringe, or leave it in the package, not recognizing its use. Choosing a Filter/Purifier While the simplicity and weight reductions of boiling and chemical treatments for survival water treatment are appealing on their face, in reality, the drawbacks of these methods really make them next-to-last resorts3 for survivors who know what they’re doing, except under limited circumstances Read the rest: https://www.patreon.com/posts/water...paign=postshare_creator&utm_content=join_link Continue reading...
