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Aqua Rain Water Filter

Compare Before You Buy!
Before you purchase an Aqua Rain Water Gravity Filter from anyone, compare it with
The British Imperial Water Filter



Our Recent Research Has Found
The British Imperial Water Filter
To Be A Superior Product With More
Biological Protection!

We Are No Longer Carrying The
Aqua Rain Gravity Water Filter.

Compare For Yourself. 
Please Learn More:
British Imperial Water Filters

Call Us
(855) 855-1976 For more information
on The British Imperial
or The Aqua Rain

About Aqua Rain

AquaRain Gravity Water Filter will provide clean and safe water you can trust, all without having to boil your water, use potentially dangerous chemicals, or rely on man-made   energy.  Our rugged, yet attractive, stainless steel housing holds state-of-the-art high quality Made-In-USA filter elements offering the very latest in advanced ceramic technology. Safety and ease of operation are hallmarks of our design.

What could be more important than clean, safe water?

The AquaRainŽ Natural Water Filter will provide clean and safe drinking water you can trust, all without having to boil your water, use potentially dangerous chemicals, or rely on man-made energy. The attractive stainless steel housing holds the very latest in advanced ceramic and carbon water filtration technology. Here is the best part... the AquaRainŽ will produce quality drinking water for less than ˝˘ per gallon!  Safety, a long operational life, and ease of operation are hallmarks of this unique product.

High-Tech Ceramic Filter Elements

At the heart of the natural process micro-filter are high-tech ceramic filter elements specifically designed for the AquaRainŽ system. Our state-of-the-art ceramic elements filter water in a very natural way, using gravity to gently draw water down through our "cultured" ceramic stone in much the same manner as nature processes ground water through the earth.  The microfine pore structure of our ceramic media will remove dangerous organisms such as protozoan cysts (Cryptospordium, Giardia lamblia) and microscopic bacteria (E. coli, Samonelli typhus, etc...). Enclosed within the hard ceramic shell we have incorporated a concentrated bed of Granulated Activated Carbon (GAC) that contains a self-sterilizing metallic silver.  The silvered GAC bed will adsorb various organic chemicals such as MTBE and pesticides, remove chlorine compounds including carcinogenic halogens, and improve the taste and odor of the water.  To the benefit of good health, our system will also leave unchanged the naturally occurring electrolytes and minerals in your filtered water.

You can depend on the proven technology used in the AquaRainŽ and even the natural concept that it relies upon to produce safe drinking water for your family.  The AquaRainŽ Natural Water Filter is manufactured to meet NSF standards and fully achieves the USEPA requirements of a Cyst and Bacteria Water Purifier.  Best of all, the AquaRainŽ is made with loving care right here in the USA! 


The AquaRain™ Water Filtration System has been engineered to provide safe drinking water from raw water sources such as rivers, lakes, streams, creeks, ponds, wells, and cisterns. At the heart of the AquaRain™ Water Filtration System are MarathonŽ state-of-the-art ceramic elements utilizing a long-proven filtration process that is over 100 years old which will safely remove dangerous waterborne pathogens such as cysts (Cryptospordium, Giardia lamblia) and bacteria (E. coli, Samonelli typhus, etc...). These innovative MarathonŽ ceramic elements are also filled with a high grade silvered granulated activated carbon (GAC). The GAC reduces pesticides, chemicals, chlorine, color, tastes and odors, while leaving the naturally occurring minerals found in the water unaffected.

The MarathonŽ ceramic elements are carefully manufactured through a patented extrusion process that results in a very consistent, close tolerance wall thickness. This allows for accurate measurement of their remaining life and thereby maintenance of the highest level of reliability and security. Additionally, Marathon's kilns are compact and operate within very close tolerance temperature ranges. This provides extremely tight control of the ceramic's final porosity. Every batch of ceramic elements out of the kilns is tested with mercury porosimetry equipment to confirm proper pore size distribution. Each finished element is fully flushed at the factory and is tested twice in the production process to insure complete product integrity.

Traditional ceramics are produced through a slip-cast method in bulk quantities, utilizing a crude plaster of paris-style mold process. They are then fired in a high temperature kiln to harden them and open up the final pore structure. When ceramics are fired in large room-sized kilns, which have a wide variance in temperatures, the "holes" in the pore structure will vary in size, resulting in inconsistent product quality. Traditional ceramics therefore cannot achieve the consistency and reliability of our new patented process extruded ceramics.

One of the most important benefits of the use of a ceramic produced by the patented MarathonŽ extrusion process, is the consistent, symmetrical, and measurable wall thickness. This symmetry allows us to externally measure the remaining wall thickness to determine when the element has reached the end of its usable life (minimum wall thickness). Determining the minimum safe wall thickness by independent lab testing and being able to measure that safe minimum on an element in service, are absolutely critical to having a filtration system you can trust.

Unlike other filters found in the market, our deep-drawn stainless containers are formed from a single piece of heavy #304 (18-8) stainless steel and have no welded seams to trap bacteria. The large 3-gallon vessel allows for more convenient operation with fewer fillings for usable quantities of water. A new Splash Guard™ has been added between the upper "raw water" vessel and the lower filtered drinking water vessel that will deflect spilled water if the upper container should be overfilled or water splashed over the side. The addition of handles to the upper vessel facilitates its easy removal, leaving the lower filtered drinking water container as a more compact, convenient water dispenser.

How Ceramics Work

Ceramic water filters primarily work in two ways. First, surface sieving, much like a screen door, does not allow larger particles to pass through the outer surface of the filter. Second, ceramic filters operate as a depth media, providing a twisting, tortuous path like a maze, trapping contaminants within the walls (usually in the top .005" below the surface).

Wall thickness is particularly important with regard to a ceramic's performance as a depth media. The maze-like, tortuous path allows for filtration performance at an effective pore size that is much less than the actual median pore diameter of the diatomes from which the filter is made. As clogged filters are cleaned to restore flow, contaminants in the top .005" of surface material are removed. Gentle abrasive cleaning will gradually reduce the ceramic wall thickness. Filtration performance will gradually diminish as wall thickness diminishes. Eventually, filtration performance will fall below acceptable, safe levels if the filter is used with walls that have become too thin. This will occur before the filter physically cracks or breaks, making a reliable end-of-life indicator or gauge absolutely essential for the health and safety of the user.


The operation of the AquaRain™ Gravity Water Filter is simplicity itself. First, collect water for filtration from the cleanest and best possible source. This cold "raw" water is then poured into the upper container where it trickles down through the highly specialized ceramic filter elements, leaving cysts, bacteria and sediment in the outer layer of the ceramic. After passing through the thick ceramic wall, the water flows through a bed of silvered coconut shell carbon which reduces pesticides, various chemicals, and chlorine (if present), along with objectionable color, tastes and odors. The filtered water then drips into the lower storage container where it accumulates for easy dispensing with our handy NSF-listed lever-action faucet.

Our published water production rates, as well as with all other gravity water filters on the market, have been established under controlled and optimum conditions with fully wetted elements. New, dry elements will need several gallons of water run through them, sometimes 10 or 12, before they are fully wetted and reach their maximum flow rate. In normal use, water for filtration may be placed in the upper vessel in the evening and allowed to filter through overnight. In the morning, most of the water will have filtered through into the lower dispensing container. Additional water may then be added to the upper container so that a continuous process of filtration and subsequent use may be established. Keeping the upper vessel as full as possible, perhaps refilling every fifteen minutes, is essential to reach the maximum production potential. To halt the production of filtered water, simply lift the upper container and empty it. The stainless steel lid can then be placed on the bottom container which may be used as a convenient and compact counter-top water dispenser.

Over time, small particulates and bacteria will eventually clog the walls of the element and slow the production of water through the filter. When this occurs, simply remove the filter element(s) and while holding the threaded end, lightly clean the hard surface of the ceramic with a brush or the scrub pad provided. The element is then reinstalled in the upper filter vessel, taking care to not contaminate the clean water end of the elements or the bottom of the upper vessel.


Extensive independent testing is the key to proving the performance of any water filter product. The Marathon's ceramic filter media, as used in the AquaRain™ Gravity Water Filter, has been thoroughly tested by independent laboratories, government agencies and is currently under testing for NSF listing. MarathonŽ has also "gone the extra mile" by specifying an especially difficult testing program that goes far beyond that which is required. Not only have elements been tested new, as all other manufacturers test, but MarathonŽ also tests ceramics that have been abraded to their end-of-life tolerance and exposed to raw field water so that these special test elements approximate true expended parts ready for disposal, as well as testing elements actually used in a variety field conditions over their entire life. Testing of these end-of-life elements has demonstrated that the MarathonŽ ceramic gravity filter elements will remain effective and meet all mandated performance levels throughout their entire usable life.

MarathonŽ ceramic elements have been successfully tested in independent laboratories with Cryptosporidium parvum (kryp-toh-spor-id-dee-um parr-vum) for cyst removal, and with the EPA mandated Klebsiella terrigena (kleb-see-ell-a terr-ra-gee-na) for bacterial removal. What is particularly noteworthy, is that the above tests have been passed with fully expended elements, ready for disposal. The MarathonŽ filter elements have also been successfully tested against the Health Industry Manufacturing Association's (HIMA) test organism, Brevundimonas diminuta (bruh-vun-daa-moan-us da-min-u-taa), which is approximately one-third the size of the EPA bacteria test organism. MarathonŽ has gone the extra mile to insure that our product will perform as promised and remain effective in producing safe drinking water throughout its entire life. To the best of our knowledge, no other manufacturer has dared to test in this way and publish the results of this type of end-of-life testing.

The MarathonŽ filter elements used in the AquaRain™ Gravity Water Filter are filled with the highest grade of silvered coconut shell granulated carbon. The coconut shell carbon has been acid-washed and de-dusted, making it some of the cleanest carbon available. The silver-carbon is manufactured to meet NSF 42 requirements for the reduction of pesticides, chemicals, chlorine, color, tastes and odors.


AquaRain™ Gravity Water Filters offer several unique innovations that set them far ahead of all other gravity water filters:

Patented Extrusion Process: Marathon's patented extrusion process produces a perfectly formed ceramic "tube" that has exacting characteristics. The wall dimensions and concentricity are tightly controlled, allowing an exact external measurement of the remaining wall thickness.

Accurate Kilns: The MarathonŽ elements are fired in compact computer-controlled kilns which allow complete and accurate control of the porosity of the finished product. The firing of the ceramic is one of the most critical steps in the process that determines the final performance of the ceramic filter element. Bulk firing in large room-size kilns cannot provide the consistency that equals highly reliable performance in the finished product.

End-Of-Life Gauge For Safety: The MarathonŽ filter elements incorporate an end-of-life caliper gauge conveniently snapped onto each element. When this highly accurate gauge can easily slip off of the ceramic element, the thickness of the ceramic wall has been reduced through cleaning to the point that we recommend replacing the element. The end-of-life measurement is possible only because of Marathon's unique patented extrusion process, which produces a consistent and measurable finished product. Laboratory testing has proven that the MarathonŽ ceramic element will be safe to use, all the way to the element's measured end-of-life.

Splash Guard™: The AquaRain™ Gravity Water Filter incorporates a special feature not found on any other stainless gravity water system. The upper vessel that holds the questionable water has a stainless steel Splash Guard™ formed on the bottom of the housing that will deflect splashed or overfilled water away from the lower storage area holding the filtered water. Since frequent filling of the upper vessel aids in maximum production, the Splash Guard™ adds extra insurance to the daily operation of the AquaRain™ Gravity Water Filter.

Easy Lift Handles: Two solid stainless steel handles have been added to the upper housing to allow easy removal for cleaning. The handles have been spot welded to the container with a special computer operated system that controls the process precisely, forming a perfect bond.

Simple & Reliable Faucet: The lever-action faucet used on the AquaRain™ Gravity Water Filter is very easy to use with a simple push of the lever to draw a cup of clean water. The lever may also be flipped up to lock it in the open position for high flow dispensing of larger quantities of water. The simple yet functional design of this American made, NSF listed faucet, makes it a very reliable part of the AquaRain™ Gravity Water Filter. You can depend on it.

Questions and Answers

Q: What is the difference between the Katadyn and the AquaRain™?

A: The Katadyn TRK Gravity Water Filter is a very good filter and the ceramics are of good quality. The Ceradyn ceramic filter elements used in the TRK have a separate, less rigid end-of-life gauge similar to ours and their ceramics are of similar hardness and overall quality. There are several important differences however. Here are a few...

Our MarathonŽ ceramics have a much smaller pore size than the Ceradyn and thus a correspondingly higher performance in removing smaller pathogens. The Ceradyn elements are also filled with a silvered quartz gravel, while our MarathonŽ elements are filled with a high quality silvered granulated carbon made from coconut shells that will reduce chlorine and other halogens if present, taste and odors, color, and some pesticides, chemicals and organic compounds.

The rugged yet attractive AquaRain™ housing is constructed of heavy duty 18-8 stainless steel while the Katadyn TRK is made of more difficult to sanitize plastic.

Lastly, the Katadyn system uses only three ceramic elements and costs more than our AquaRain™ Model 400 with four high quality ceramic elements in a stainless steel housing.

Q: What is the story on "absolute" micron ratings?

A: There is a great deal of confusion regarding "absolute" micron ratings. Just how much of a reduction efficiency should be considered adequate for an "absolute" rating? Is 99.9% (3 log) sufficient, or would 99.9999% (6 log) be more appropriate, since it matches the EPA bacteria requirement? Should a filter be rated by its ability to remove particles of a certain size, or should it be challenged with live organisms of a particular size? Should a filter be tested only when it is new, or should the ratings be based on its end-of-life performance? The fact is that there is no industry or government standard for "absolute" filtration performance.

The MarathonŽ filter elements used in the AquaRain™ Gravity Water Filter have been extensively tested against live organisms using expended end-of-life elements. We believe this form of testing to be the most stringent, since it tests the filters in a manner similar to the way they would actually be used under worst case conditions. When testing against the .5-.6 micron organism Klebsiella terrigena, EXPENDED MarathonŽ elements demonstrated a 6.6 log reduction (they achieved 8.9 log reduction when new). The EPA only requires a 6 log reduction from NEW elements, which we greatly exceeded under extreme pressures of up to 90 psi, well above normal test pressure. At the very low pressure of ˝ psi found in our gravity filter, the efficacy would be far greater still. Does this mean that the MarathonŽ filter elements have an "absolute" rating of only .5-.6 microns? Expended MarathonŽ filter elements have also been tested against the Health Industry Manufacturing Association's (HIMA) test organism, Brevundimonas diminuta, and achieved a 99.99815% reduction (99.9999% when new). Since this organism is .2-.3 micron, should we claim this as our "absolute" rating? British Berkefeld literature lists the "absolute" rating of their filter at .9 microns and their U.S. dealers claim "absolute" performance at .5 microns. Their own factory literature claims only 99.9% efficiency at the .5 micron level. Is 99.9% sufficient for claiming an "absolute" rating? The bottom line is that the AquaRain Gravity Water Filter System, using MarathonŽ filter elements, will outperform all other gravity-fed ceramic water filter systems. Since there is no standard for "absolute," YOU will have to decide what level of protection you want for yourself and your family.

Q: How much water will the filter produce?

A: We have established a water production rate of 25-30 gallons per day for the AquaRain™ Model 400. This maximum production figure has been established under controlled and optimum conditions with clean and fully wetted elements and relatively clear water. Keeping the upper vessel as full as possible, perhaps refilling every fifteen minutes, is essential to reach the maximum production potential. In normal daily use, a more conservative production figure of approximately one gallon per hour would be appropriate for the Model 400 Filter.

Small particulates and bacteria will eventually clog the walls of the element and slow the production of water through the filter. Proper cleaning will restore the filter to full flow rates, each and every time.

Q: How long do the filters last?

A: There are two parts to the filter elements; the ceramic shell, and the granulated carbon filling. Cleaning of the ceramic shell is what wears out the ceramic portion of the filter. Over time, particulates and bacteria clog the microscopic pores of the ceramic, slowing down the flow rate. Occasional cleaning with a small brush or the enclosed green scrub pad will restore the original flow rates. Our ceramic formulation is very hard and will endure many cleanings, perhaps over 200, if moderate care is taken and light pressure is used. In normal usage, this equates to thousands of gallons of water that can be filtered.

The inner carbon filter works by adsorbing and/or reducing certain chemicals, and has a finite lifetime based on the concentration of the compounds being reduced. Generally speaking, the carbon capacity should exceed the life of the ceramic portion of the filter when processing normal chlorinated water. Please note that when the elements are exhausted from reducing chlorine, that they are still fully effective for the removal of cysts and bacteria, provided the remaining ceramic wall thickness still has useful life.

Q: Will the filters remove salt from the water?

A: No. Our ceramic elements leave all of the naturally occurring minerals intact and will not single out salt alone. This is generally not a problem with most water sources. If salt is a problem with all of your local water sources, you can collect rain water and use it to dilute or replace your other sources. Collected rain water must still be filtered through the AquaRain Filtration System to insure its safety.

Q: Will the filters remove lead or heavy metals from the water?

A: No. Generally this is not a concern. Heavy metal contamination is not commonly found to be a problem in surface waters. Always try to collect the best water available in clean waterways from a known acceptable source.

While heavy metals reduction is possible, we believe that when all of the factors are considered, the addition of specialized heavy metals reduction media will not necessarily be an enhancement to our Water Filtration System. Special heavy metals reduction media (often ATCTM or ATSTM lead reduction products from Englehard), will displace volume that could have been used for high quality carbon. This reduces the overall amount of VOC and chlorine reduction that the filter elements are capable of achieving. Further, the fine, powdery particle size of heavy metals reduction media will make the filtration media more dense, thus restricting the flow of water and slowing output. We feel this is not a good trade-off unless there is a legitimate priority for heavy metals reduction, as otherwise the reduction media would actually render a filter LESS effective with these additives.

Q: Will the filters remove nitrates from the water?

A: No. Nitrates are similar to dissolved minerals, and ceramics will not remove them. Nitrates, when concentrated, primarily affect small infants and the aged. Generally, nitrate problems can be avoided with careful water collection procedures, avoiding areas where livestock gather or where heavy farming with chemicals is practiced. Use rainwater when in doubt.

Q: How do you clean the ceramic elements?

A: The ceramic elements are very easy to clean. You simply remove them from the upper container, and while holding the threaded end of the filter upright, brush lightly downward toward the end cap. Rinse the element after you have lightly cleaned the surface, taking care that contaminated water does not enter the hole in the threaded end of the filter. Occasionally it will be necessary to lightly abrade the surface to restore full flow rate, perhaps after 3 to 5 brush cleanings. If the inside of the element becomes contaminated during the cleaning process, boil the element for 5 to 6 minutes (longer when above 4000 foot elevation), allow them to cool, then reassemble the filter. When reassembling the elements into the upper container, be sure to keep all exterior surfaces clean and free of contaminated water. Do not allow the lower filtered water storage container to become contaminated, as disease-causing pathogens may then be present.

Q: How do you store the filter after use?

A: Simply remove the filter elements and allow them to completely air dry for at least 24 hours or more. Dry the containers and all parts and then slide the lower container into the upper container to nest them together. Pack the elements carefully with padding to avoid breaking them. For maximum protection, we recommend that you repack the filter system into the original box using the original packing materials when possible.

Q: Why do the sides of the AquaRain™ Filter housings appear magnetic, but the lid and bottoms do not?

A: Our stainless housings are deep-drawn from a single piece of #304 (18-8) stainless sheet metal. A hydraulic press forms the can shape into a high powered magnetic form, drawing the stainless down across the iron sides of the mold. A few very fine particles of magnetized iron will adhere to the walls of the stainless when the magnetic form separates to remove the housing from the mold. These particles do not affect the final product in any way whatsoever and will gradually be cleaned away over time. A single piece deep-drawn housing is always superior to a welded design, having no welds to alter the stainless formulation or seams to trap bacteria and contaminants.

Q: How long have AquaRain™ and MarathonŽ Ceramics been in business?

A: AquaRain™ (originally AquaCleer) was started in 1988, providing advanced water treatment systems designed to meet difficult treatment challenges in light commercial and residential environments. Development of the AquaRain™ Gravity Water Filter began in February of 1998, when we explored methods of treating water without the use of chemicals, pressure, or man-made energy. We shortly arrived at the conclusion that ceramics held the promise of meeting our design goals. AquaRain™ then began a worldwide search for the best ceramic filter element, ordering samples and comparing independent test data. MarathonŽ Ceramics was selected as our manufacturer of choice in July of 1998, and we began working with them to develop the advanced ceramic filter element that is now used in the AquaRain™ Gravity Water Filter.

MarathonŽ Ceramics was originally formed as a division of MSR (Mountain Safety Research), Inc. in December 1997, though they had previously produced ceramics as a department of MSR for internal demand for over two years. MSR is a subsidiary of REI (Recreation Equipment Inc.), the world's largest cooperative-owned retailer with over 5 million members.

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