Living in a rural southern area of the eastern United States I am keenly aware that we are usually the first to lose power and last to regain power in any natural calamity. A few years ago, we lost power for over a week. With recent environmental catastrophes like Sandy et al, I have been reminded of a significant deficiency in my family survival preparations, water filtration. I am not getting into the nitty gritty of the micron levels of filtration (most units reviewed were .2 microns or better) or the science of the systems. This is a layman's attempt to navigate the troubled waters of filtration systems. At the end of my research, I contemplated ditching the whole idea and simply boiling pond water, filtration systems be hanged. I have a basic hiking pump water purifier along with gallons of Clorox and even iodine tablets but for long term water purification, I have felt naked since actively pursuing a mind set of preparation. Simply put, without hydration, you die, and not pleasantly. With this in mind I determined it was time to make the investment in a gravity drip system for my family. Most of you familiar with the basic concepts of preparedness are probably aware of the options available for home use. In my typical OCD research mode, I determined to find the "best" option for my family based on the following criteria: economy, availability of filters, purification capabilities and durability. I dedicated one evening of solid research to ascertain the "best" gravity drip water filtration unit. My bias initially was towards the "Big Berkey" system of filters. It is ubiquitous on the Internet. But what I learned is that the Big Berkey system may be in fact one of two very different systems, first there's the "Berkey" system which appears to be the most common system. This product's stainless steel housing is made in India, but the filters elements are made in the USA. This was my first choice based solely on reputation. There exists much diffuse debate as to the effectiveness of the Berkey black charcoal based filters and their mysterious manufacturing components. No one on the Internet was able to ascertain or say with any definitiveness what the black filters were made of. On a personal note, I think it'd be nice to know what's filtering my drinking water. The unit I was looking at was the Royal Berkey and was a two filter system encased in a lovely, shiny stainless metal container. The price seemed steady at $270.50 from a number of different vendors on line. The replacement black filters are in the $50 to $60 range with an expected life of up to 6,000 gallons and they are reportedly re-cleanable. The ceramic filters 9" run from $33 to $48 per unit and are impregnated with silver, expected life 1,200 gallons. These filters are also re-cleanable. The silver is present in the ceramic filters to inhibit bacterial growth in the filter. And than there's the the British Berkefeld system, which has been utilized for years and years, and is made in England. This system has been utilized in the remote, water dirty areas by the likes of the Red Cross and other aid agencies. This, to add to the confusion, is also imported by New Millennium Concepts Ltd., and others as well, their listed price for the basic camping model was $337, not sure if shipping was included. British Berkefeld also makes a fluoride and arsenic filter, the PF-2 and PF-4 which run in the neighborhood of $25 a piece. The second major system I researched was the AquaRain filtration system, in particular the Model 400 (price around $229.) and 404 (price around $310). The primary difference between the two is two filter elements in the Model 400 and four in the model 404, obviously the 404 has a higher rate of filtration. I was drawn to this system because of its purportedly being made in the United States and its use of ceramic water filters which have greater life than the charcoal based systems. The replacement filters I found ran from $47 to $57 for the ceramics. But, what threw me off of this product was others reporting that it was not entirely made in the United States and reports of some units breaking in the field. Customer service was purportedly prompt, which was encouraging. The Aquarain systems received high praise for their filters. The ceramic filters are made utilizing a computer controlled manufacturing process for greater uniformity. Expected life is at least one year of use with thousands of gallons of water filtered with up to 200 light scrub cleanings as necessary. I further researched the low end of gravity drip filters the Doulton's and the Monolithic systems. The Doulton is the poor man's Berkey. There are mini versions along with more family oriented sizes, one model--the SS-2--can filter 10 gallons a day and lists at $179. The filters looked pretty affordable as well, in the $30 to $40 range. I also found mini versions of these systems which received high praise by many reviewers. These products are made in the United Kingdom as well. For the budget minded there is the Monolithic system. The Monolithic system is nothing more than two five gallon buckets, covers with holes, filters and a spigot. Their cut rate cost was less than $60 on some of the web sites that I found. I also found a do it yourself model, estimated cost would be around $100 to a $120. It truly is a sad day when it costs less to buy the complete system than it would to do it yourself. The web site was called "Southern Belle Prepper." She gave step by step instructions on how to make your own gravity drip system from easily acquired resources both local and Internet. I finally after hours of frustration and reading claims and counterclaims of superiority chose the Katadyn TRK Ceradyn system. It is a system that does not have the nice shiny chrome look of the Berkey's, Aquarain or Doulton systems but is composed of a BPA free plastic and utilizes three upright ceramic filters, this is the primary difference between it and the Katadyn Gravidyn system which uses charcoal based filters. The Katadyn systems are Swiss made, and the Ceradyn model has a 13 gallon per day filtration rating. The standard price for this unit was $317 and some change, but I was able to find it on ebay for $240 with shipping. Emergency Essentials had run a sale listing it at $249 during the month of January. I was pleased that the Ceradyn system had the ceramic filters because of what I note as greater longevity of filters. The ceramic filters have an expected life of up to 13,000 gallons per filter. The price range for replacements was $58 to $65 per ceramic filter, well within the range of the comparables. I confess that I often read the reviews found describing the pros and cons of products on line. I was impressed with the words of one user of the Katadyn Ceradyn system who had been a missionary in the undeveloped world describing this as the best system money could buy. I also appreciate that the Katadyn systems are used by the U.S. armed forces and International Red Cross. The filter life was a major factor in my choice of the Katadyn TRK Ceradyn system. More gallons for the money. In then end I determined that your gravity filtration system choice is a highly personal one, and I almost laugh as I write this because it sounds pretty silly. But, folks who prepare tend to be folks who research and want the most bang for their buck. When I started my research and ultimately made a purchase, I wanted someone to tell me what to buy. What I found was a frustrating maze of information for a lot of great items. I ultimately chose a model that I think fits my family's needs, is portable, efficient and with great accessibility to filters. One general rule that I would encourage others to consider is ceramic is preferred to charcoal, especially silver impregnated ceramic as it has excellent longevity and can last thousands of gallons of filtered water. Another factor to consider is filter availability, most if not all of the major players filters can be found on line and on amazon.com. Some of the filters are even interchangeable, e.g., an Aquarain ceramic filter in a Big Berkey unit. I know that I may have offended some with my lack of scientific detail, but I reviewed the specs of the various models and on a basic level, they are all pretty good. And they are all certainly an improvement on boiling and iodine treatments. Do your own research and draw your own conclusions. But whatever you do, don't go thirsty.