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Gravity Water Filter/Purifier Comparison Chart

CompanyNMCLAquaCeraAquaCrockPro PurDoultonAqua RainKatadyn
ModelBig BerkeyCeragrav-LP5AquaCrockPro BigGSS-2Model 400Gravidyn

[A] = Purification Standards: Element must remove/inactivate all types of pathogenic organisms. Specifically, element must remove two species of virus to 4 Log10 (=> 99.99%) and remove pathogenic bacteria to 6 Log10 (=> 99.9999%) and remove cysts to 3 Log10 (=> 99.9%). This makes Berkey systems the only true gravity fed purification systems.

Purification Challenge: The Standard has selected 3 types of challenge organisms: Bacteria (Klebsiella terrigena), Viruses (Polio and Rota) and Protozoan Cysts (Giardia or Cryptosporidium).

  1. VIROLOGY - Demonstration of a 4 Log10 (99.99%) reduction is required on the combined polio/rota virus challenge matrix.
  2. BACTERIOLOGY - Demonstration of a 6 Log10 (99.9999%) reduction is required for the Klebsiella terrigena bacterial challenge.
  3. CYST REMOVAL - Demonstration of a 3 Log10 (99.9%) reduction is required for the cysts using Cryptosporidium or Giardia.

 

[B] = Number based on 2 gallons per day per person, system used 12 hours per day.

[C] = Aqua Crock, Doulton GSS-2, Ceragrav LP-5 all use Doulton Filter Elements - life expectancy is 525 gallons or 6 months, whichever occurs first.

[D] = Claim made is 2 years or 3,000 gallons; while the manufacturer of their Doulton filter elements states the life expectancy is 535 gallons or 6 months whichever occurs first.

[E] = While the company claims their elements will last for 3,000 gallons on their comparison chart, we used the claims of the manufacturer, which state that the life of the elements is only 1,500 gallons or 12 months whichever occurs first.

[F] = Calculation based on each element producing 3 gallons when used for 12 hours per day during 365 day maximum recommended time limitation.

[G] = Calculation based on each element producing 12 gallons if used for 12 hours per day during 182 day maximum recommended time limitation.

[H] = Cost per gallon presumes maximum gallon claims reached prior to "replacement time limitation" above and calculated based on "max daily output" above, whichever is less or occurs first.

[I] = Successfully demonstrates removal of microscopic red food coloring particulate from source water at 1 tablespoon of red food coloring per gallon.

[J] = Test is designed to determine if high turbidity (larger particulate) source water will clog up elements which may render them ineffective during actual emergency conditions. 1 tbsp carbon dust per gallon. Flow rate reduction of <25%=Pass, >25%=Fail.

[K] = NSF Claims: No listing on NSF website as of publication date. NSF has confirmed that ProPure has not been certified by their organization

Where information was available and published, this information was used. Where information was not available, information was calculated, such as in F and L above, using the available published information. Where published information on systems was in conflict with the published information by the manufacturer, such as in C, D, and E above, items are highlighted in orange.

Data based on manufacturer's life expectancy claims rather than the claims of the manufacturer's customer. Information collected from websites, corporate literature, internal testing and outside independent sources is believed to be accurate at time of publication (5-15-12). Neither this chart nor it's producer assume any liability, implied, expressed or assumed.

There are other gravity fed filter systems that claim they are not to be used with microbiologically unsafe or questionable water. We chose not to include those systems in this comparison chart.

Virus Removal [A] Yes No No No No No No
Element Rating Purifier [A] Filter Filter Filter Filter Filter Filter
Base System Cost $263 $139 $399 $239 $229 $239.99 $219.95
Max Daily Output (Gal/Day) Base 84 10 18 9 14 12 24
Max Daily Output-Max # Elements 168 25 18 18.5 20 24 24
Approx. People Served [B] 42 6 5 4 5 6 6
Maximum Gallons/Element 3,000 535 [C] 535 [C,D] 1,500 [E] 535 [C] 1095 [F] 730 [G]
Replacement Time Limitation No Time Limit 6 Months [C] 2 Years [C,D] 12 Months [E] 6 Months [C] 1 year [F] Up to 6 months
Price of Elements (Each) $54.50 $30.00 $36.00 $49.50 $36.00 $42.99 $56.00
Approx Cost Per Gallon (Cents) 1.8 5.6 [H] 6.7 + electric [H] 3.3 [H] 6.7 [H] 3.9 [H] 7.6 [H]
Maximum Element Capacity 4 5 3 4 4 4 3
Food Color Test [I] Pass Fail Fail Pass Fail Fail Fail
Turbidity Flow Rate Test [J] Pass Pass Pass Pass Pass Fail Pass
Test Results Available Yes Yes Yes No Yes Yes Yes
Tested to NSF Standards Yes Yes Yes Yes Yes Yes Yes
NSF Certified Claimed No No No Yes [K] No No No
Guarantee 6 Mos (elem 2-Yr) None Published 1 Year Ltd. 2 Year None Published None Published None Published
System Cost-Max Elements $363 $274 $399 $338 $299 $319.99 $219.95
System Material AISI 304 Stainless HDPE Ceramic Stainless AISI 304 Stainless Stainless Silicone
System Production Plasma Welded Molded Kiln Deep Drawn Plasma Welded Deep Drawn Molded
OTHER INFORMATION
Element Composition Proprietary Formula Ceramic / Carbon Ceramic / Carbon Ceramic / Carbon Ceramic / Carbon Ceramic / Carbon Ceramic / Carbon
Number of Elements 2 2 3 2 2 2 3
Element Height 9" 7" 5" 9" 7" ~9" 10.4"
Elements cleanable Yes Yes Yes Yes Yes Yes Yes
Storage Tank Capacity (Gallons) 2.25 3.5 Not Stated 2.75 2.25 3 2.6
Electricity Required No No Yes No No No No
Plumbing Required No No No No No No No
Post Filters Yes Yes Yes Yes Yes No No
Height 19.25" 28.5" 17.5" 21.5" 19.25" 20.5" 18"
Diameter 8.5" 11.25" 11" 9.25" 8.5" 11" 11"
Dry Weight (Approx.) 6 lbs 5 lbs 26 lbs 5 lbs 5.5 lbs 7 lbs 6.5 lbs

Quick Links:

General Questions
System Setup and Maintenance
Black Berkey Purification Element Questions
Ceramic Filter Questions
Troubleshooting and Other Questions
Viruses FAQ

General Questions

How durable are the systems?

The exterior chambers are made of high-grade polished 304 stainless steel making them rugged enough to handle camping trips and college dorms yet elegant enough to complement your finest décor. The Berkey Light system is made of a non-BPA copolyster.

What are the limitations found in other types of water filtration systems?

Carbon block, paper and certain resin based filters:

  • Most commonly used filters are not re-cleanable
  • There is no feedback mechanism for filter replacement
  • Most do not remove pathogenic bacteria
  • Most popular systems provide only 40-700 gallons (150-2,660 liters) before the filter must be replaced

Distillation:

  • Removes beneficial minerals from water
  • Does not remove VOCs (chemicals found in herbicides, pesticides, and fertilizers)

Reverse Osmosis:

  • Removes beneficial minerals from water
  • Does not remove pathogenic bacteria
  • Filter is not re-cleanable
  • There is no feedback mechanism for filter replacement and reservoir tank can become a breeding ground for bacteria

Downsides to These Other Systems: Virtually all of these systems become useless during emergencies when power and or water pressure is lost.

Bottled Water: Tap water is considered an acceptable source; many bottled waters contain high levels of bacteria and the industry is virtually unregulated.

How do I determine which Berkey system is right for my needs?

The most popular small family (3 people) model is the Big Berkey system. The most popular medium (4 people) to large family model (6 people) is the Royal Berkey system. The Imperial Berkey model is designed for small to medium sized groups (6-12 people) and the Crown Berkey model is more useful for medium to large groups (12 people and up) and can service from 75 up to 150 people per day.

What are the basic differences between the Berkey Light and the other stainless steel systems?

The Berkey Light system is designed for outdoor use therefore it is about three pounds lighter in weight than the equivalent capacity of our stainless steel system. The Travel Berkey system is also designed for outdoor use and is the smallest of the stainless steel systems. It is compact enough to fit within a suitcase because unlike the Berkey Light system, the upper chamber nests within the lower chamber during travel. This is the preferred system when mobility is a big issue.

The four multi-use systems are designed for indoor everyday use so they are of a heavier construction than the above systems but these systems can also be used outdoors or during unexpected emergencies when a source of potable water may not be available.

Historically, who has used these filtration systems?

  • The Royal household in England
  • Tens of thousands of US and Canadian citizens
  • Populations in over 140 countries worldwide
  • Relief Organizations such as UNICEF, the Peace Corps, Missionary organizations and Red Cross Societies Internationally.
  • Hunters, campers, adventurers and explorers.

I will soon be leaving the country. Is there a way to test my Berkey system to make sure it is working properly?

Yes, anytime you plan on taking your system out of the country we advise that you always perform the following test prior to leaving. You should test your filters by filling the upper chamber with water then add a tablespoon of food coloring for every gallon of water within your upper chamber. If the food coloring is removed entirely, your filtration system is working properly. If not, check to make sure that the wing nuts on your elements are securely tightened then re-run the test.

By the way, always prime new purification elements before leaving the country, as you may not have enough water pressure to be able to prime the elements at your destination.

Does the system remove beneficial minerals?

No.

System Setup and Maintenance

What should I do to maintain the system properly?

  • Wash lower chamber once per month with soapy dishwater.
  • In areas with hard water, calcium scale may build up on spigot and chambers after prolonged use. To remove, soak affected part(s) in vinegar or a 50-50% mix of vinegar and water for about 15 minutes. Wipe away calcium scale with a ScotchBrite pad or soft brush then wash with soapy dishwater and rinse.

I have been using my system for about six months and the flow rate has slowed down considerably. Do I need to replace the elements?

No, unlike other filtration elements Black Berkey purification elements are re-cleanable. What typically causes the filters to drip slowly is turbidity and sediment clogging the micro-pores of the purification elements. Simply remove the elements from your system, scrub the exterior of each element with preferably a white ScotchBrite pad or stiff toothbrush. Simply scrub a section of the filter until you see a bit of black on the white pad then move to the next section. It's simple to do and takes less than a minute. Then re-prime each element and reinstall them. Your problem should now be fixed.

I installed my PF-2 elements but my water is a bit cloudy, and why does it have a bad taste?

Insufficient re-conditioning (priming) may result in an undesirable taste and/or cloudiness in the water. The odd taste is from process dust that may not have been washed free from the elements during the conditioning process. Please remove the PF-2 elements and re-condition them for no less than 60 seconds (longer may be needed) on both ends. This should expel any residual process dust and fix the problem.

How often do the Black Berkey purification elements need to be replaced?

Each element has an expected life of 3,000 gallons or 6,000 gallons for a set of two.

How do I know when it is time to replace the elements in my system?

The best way to gauge when to replace the filters is to do the following:

  1. Multiply the number of filters in your system by 3,000 gallons to get Total Gallons For All Filters within the system.
  2. Next keep a track of how many times you need to refill the upper chamber in one week.
  3. Then multiply that figure times the capacity in gallons of your particular system (for example the Berkey Lightª system is 2.75 gallons) to determine Total Gallons Used Per Week.
  4. Finally divide the Total Gallons Used Per Week into the Total Gallons For All Filters and that will tell you how many weeks before the filters should be replaced.
  5. Next calculate the future date for replacement (52 weeks per year) and write that date on a sticker and attach it to the bottom of your system for future reference.

By the way, if you have been using your system for some time now, you can still use the above formula to determine when to replace the elements. Just count forward from the date you purchased your system.

How do I determine when the ceramic filter element must be replaced?

Replace the elements when the carbon has been exhausted or if there is a significant change in diameter of the ceramic after cleaning. Anytime a crack in the ceramic occurs, the integrity has been lost and the filter must be replaced.

Black Berkey Purification Element Questions

How do I prime my Black Berkey elements for use or storage?

Click on this link to learn how.

What are the Black Berkey elements made out of and how do they work?

Without getting too complex, several methodologies are utilized by the Black Berkey purification elements. The elements are composed of a formulation of more than a half dozen different media types constructed into a very fine matrix creating millions of micro-fine pores. The pores are so small that pathogenic bacteria, cysts, parasites, sediment and sedimentary minerals are not able to pass through them. The media formulation both "absorbs" some contaminates and "adsorbs" other contaminates. Next, heavy metals ions (mineral molecules) are extracted through an Ion exchange process where they are essentially electrically bonded to the media. Finally, our filter elements are designed such that each water molecule can take several minutes to pass through the filter elements whereas these molecules passing through other filtration systems pass through those filters in literally microseconds. The longer the water molecules are in contact with any media, the greater the removal of the various contaminates.

What is the shelf life of the Black Berkey purification elements?

The shelf life of the Black Berkey elements is indefinite. In other words they will last until you need them. We would advise however, if you intend to store them for a long period of time, that you store them in a zip-lock bag. This is because they are powerful enough to absorb contaminants from the air, which could reduce their expected life if you have a lot of airborne contaminants in the area in which they are being stored. A zip-lock back will prevent the above from occurring.

What is the Micron Rating of the Black Berkey purification elements?

With respect to the micron rating, we do not use or publish a micron rating for the Black Berkey elements for the following reasons.

There is much confusion with respect to nominal and absolute micron ratings. An absolute micron rating is one that states the maximum pore size expected within an element. The nominal micron rating is the average pore size within the element. This means that if 90% of the pores are .02 microns and ten percent are 2 microns, one could claim the nominal micron rating as .2 microns, which would imply that pathogenic bacteria and parasites would be totally removed. But in reality the bulk of the water would channel through the larger 2-micron pores and thereby allow both bacteria and parasites to pass through. Therefore a nominal micron-rating claim can be very misleading.

With respect to the absolute micron rating, there is also confusion because there are two different standards to determine absolute; in the US the standard is 99.9% removal, but the international standard in 99.99% removal or 10 times greater removal.

Clever marketers of products can use the confusion over the above differences to make product "A" appear to be better than product "B" when product B may be far superior in reality. For example, we used to report an absolute rating using the international standard because we have a large international customer base. Several years ago we published a rating on our ceramic filters. A particular company began to publish that our elements were .9 microns whereas theirs were .2 microns. However, our micron rating was based on absolute (international) while theirs was based on a nominal(US)rating. When tested at Spectrum Labs, it was found that at the .2 to .3 microns range our filter removed more particulate than the other brand. Unfortunately many people make there purchasing decisions based on a micron rating that can be legitimately distorted and to a significant degree.

We soon became weary of trying to explain the above to our customers and so we decided not to participate any longer in publishing a micron rating. Rather, we think an absolute pathogenic bacteria removal rate is a far better gauge because it is far more difficult to abuse. Based on that criterion, the Black Berkey elements remove greater than 99.9999999% of pathogenic bacteria such as E.coli. To our knowledge, no other personal filtration element can match that capability. In fact, the Black Berkey elements are so powerful, they are unique in their ability to mechanically remove food coloring from water.

Many news stations have reported that pharmaceuticals have been found in the water of many cities in the U.S. Do the Black Berkey elements remove drugs from the water?

There are simply too many varieties of pharmaceuticals that a water filtering system could be tested for to see how it performs. By too many, I mean it is impossible to test for them all. However, we do know from testing, that the purification process used by the Black Berkey elements remove more pollutants than any other system available on the market today. In other words, if there are any systems that remove pharmaceuticals from the water, the Black Berkeys are one of them.

Do the Black Berkeys remove Chloramines?

The company has been researching labs to test for chloramine removal for some time. The difficulty is that many labs do not know how to test gravity filter systems for chloramine removal. In addition, since they would test the black berkey filters for the entire life, testing costs for the labs that do have the capabilities have been quoted extremely high. So, it is not that the berkeys will not remove chloramines, it is simply we do not know yet. We believe they will and the tests will prove this.

What we can state is that given research, the black berkeys should significantly remove chloramines in water. This is based on the Central Coast Water Authority website and others which state that a carbon filter will remove chloramines as long as it is made of high quality carbon and sufficient contact time is allowed; both of which are the case for the black berkeys.

It appears that there is a slight dimple in one of my Black Berkey elements, is this filter flawed?

No, The Black Berkey purification elements are about twice as thick as are standard gravity filter elements. This is a built in redundancy or overkill, if you will. The minor dimple in the filter should not cause any decrease in the elements efficiency. However to check its performance, make sure the wing nuts are on tight and do the following:

Test your filters by filling the upper chamber with water then add a tablespoon of food coloring for every gallon of water within your upper chamber. If the food coloring is removed entirely, your elements are working properly. If not, check to make sure that the wing nuts on your elements are securely tightened then re-run the test.

It is time for me to replace my filter elements but I have a different brand name of gravity filter. Will the Black Berkey elements fit my system?

Yes the Black Berkey purification elements are interchangeable with other gravity systems and the PF-2 filters can be used as well.

Ceramic Filter Questions

Why are our ceramic elements unique?

  • Berkey ceramic filters have been in continual use since 1827
  • Silver impregnated: Inhibits Mitosis or Bacterial Grow-Through.
  • Particulate reduction:
    • .2 Nominal
    • @ .2 Microns 98%
    • @ .3 Microns > 99.7%
    • @ .5 Microns >99.9% (Spectrum Labs)
  • Removes >99.99% of Cryptosporidium, Giardia, E. coli, Vibro Cholerae, Salmonella, Dysenteria.
  • Toxicological extraction is commonly the most difficult area of the NSF testing standards to satisfy. This shows that the filter does not re-contaminate the water. Many other ceramics have not passed and may not be capable of passing the NSF material extraction test. The Ceramic shell of our Super Sterasyl element is an NSF Listed Component and is manufactured to meet NSF standard 42 for materials.
  • Carbon Core: Reduces bad tastes and odors as well as pesticides, herbicides, organic solvents and trihalomethanes.
  • Ceramic elements may be cleaned many times to prolong the life of the filtration elements.
  • No other ceramic manufacturer may claim the above

When and how do I clean the ceramic filter elements?

If the time it takes for the water to filter into the lower chamber substantially decreases, simply hold the ceramic element under clean running water while scrubbing lightly with a ScotchBrite pad or toothbrush. Cleaning should be performed evenly by working from the threaded mount down.

What happens when the carbon in the ceramic becomes exhausted?

The carbon will be unable to reduce chemicals, foul tastes and odors in the source water.

  • When the carbon is exhausted, the ceramic shell will continue to remove pathogenic bacteria and turbidity.

Troubleshooting and Other Questions

I just purchased a Berkey system but the system is hardly filtering any water at all. Am I doing something wrong?

Typically the problem you are experiencing is due to high water tension, which prevents the air from being purged from the micro pores of the new purification elements. Included with your Black Berkey elements is a priming button and instructions for use. Please remove and prime your purification elements, reinstall them and that should fix the problem.

I just purchased a Berkey system but didn't receive a priming button. Instead, I think I received an extra black washer in the box. The instructions say to use the tan colored priming button. What gives?

Please check in the box which held Black your Berkey purification elements. The box should contain two (2) elements. Attached to each element should be a rubber washer and a wing nut. Also in the boxes should be what could looks like another single black rubber washer. This is your priming button. It is thicker than the washer and the center hole is smaller. This black priming button can easily be confused with a washer; so we asked the manufacturer to change the color of the priming button back to tan.

How do I prime the Black Berkey Purification Elements when water pressure is unavailable?

The micro pores on the Black Berkey purification elements are extremely small, in fact they are small enough to filter food coloring out of water. The benefit from having such extremely small pores is greater efficiency at removing pathogenic bacteria and other contaminates. The downside is that too much water tension can require that the purification elements be primed before they will flow properly. When you receive the purification elements, they are dry and air is trapped within the tiny micro fine pores. In certain parts of the world, water has more water tension than in other places and this can change from season to season. The higher the water tension, the more difficult it is for the water to force the air out of the micro fine pores using gravity alone. The pores that have air trapped within them do not allow water to pass through and therefore become an inaccessible passage for the water. This then causes the system to either filter very slowly or not at all.

Before traveling to and using the system in an area without water pressure we recommend that the purification elements be primed using the priming button. If this however is not possible and water pressure is not available to use the priming button method, the elements can be primed approximately 50% by using the below method. In other words using this method, the elements will not purify as fast as they will by using the priming button method however they will run significantly faster than if the elements have not been primed at all. The alternate priming method is as follows:

STEP 1: If your system is assembled, remove the purification elements from the upper chamber. Next, fill the lower chamber with water, then place the purification elements into the water in the lower chamber, upside down with the stems facing upward, and put a ceramic coffee cup (or something else that will hold them under the water) on top of each purification element stem to force the element down under the water. Let the purification elements soak in the water for several hours. This will force some of the air out of the stubborn pores. NOTE: Make sure that opening in the stems of the purification elements are not underwater as we want the water to be forced through the pores rather than entering through the hole in the stem.

STEP 2: The inside of the purification elements should now be full of water and significantly heavier. Try to keep as much water on the inside of the purification elements as is possible as you reassemble the purification element into the upper chamber by keeping the stems facing upward. Empty the water from the lower chamber and place the upper chamber back onto the lower chamber. Immediately fill the upper chamber with water.

When the purification elements have water within the bore (inside core), more force is generated to draw water through the purification element. This is because the water that drips out of the purification elements also hydraulically pulls new water into the purification element as the purification element begins to work like a siphon. Thus, in addition to the "Push" of gravity, there is also a hydraulic "pull" and this drastically improves the ability of the water to force the air from the micro pores. The above method is less efficient than priming the purification elements with the priming button but should be about 75-80% effective in clearing the blocked micro pores.

Let the water in the lower chamber run to waste and refill the upper chamber with water. Your Black Berkey elements are now primed and ready for use.

The water in the upper chamber of my Berkey system does not drain all the way. Is this normal?

Yes it is normal and not unusual for the last 1/2" to 1" of water to remain in the upper chamber. By design the water must pass through very fine micro pores within the elements in order to pass from the upper chamber to the lower. The lower the water level in the upper chamber, the lower the pressure available to force the water through the micro pores. You might have noticed that the system purifies much faster when full than when half full. That is because there is more pressure. The only way to remedy the problem would be to enlarge the pores within the filter elements. That would of course, reduce the efficiency of the purification elements. During each cycle the water left from the previous cycle mixes with the water from the current cycle and is then purified. You should not be concerned about the excess water during normal use however if you discontinue using your filter for a period of time such as during a vacation, it would not hurt to empty the upper chamber before departing.

have found that when I boil the water or freeze it into ice cubes, I sometimes get little white floating things in the water. What is this?

With respect to the little white floaters in the water, it is not bacteria but rather a problem that sometimes occurs with hard (heavily mineralized) water. When water is filtered through your system, the Black Berkey purification elements actually increase the PH of the water. This is healthful as Pathogenic bacteria and viruses thrive in acidic environments and conversely have difficulty surviving in alkaline environments. This is also true inside your body. When the PH level of the purified water is raised, the acidity of the water goes down and the water is no longer able to hold as many minerals in solution. When this happens the minerals begin to precipitate out over time and depending on the mineral composition they will either sink to the bottom or float to the top. This process is known as flocculation and the precipitated minerals are usually referred to as "white floaters". The bottom line is that this is nothing to be concerned about, the white floaters are minerals that were already in your water; they are now simply visible whereas they were previously invisible due to their suspension in an ionic form.

I did a TDS reading on the purified water and was surprised to find that the reading was about the same with the purified water as it was with the unpurified water. Is my system working properly?

Yes, a TDS meter measures only Total Dissolved Solids or minerals; dissolved solids are simply dissolved minerals in an ionic form. A TDS meter does not measure the amount of biological and chemical contaminates. Black Berkey elements are designed to leave in your water the healthful and beneficial minerals and to extract only the unwanted heavy metals such as lead and mercury as well as sedimentary minerals such as iron oxide and aluminum. Therefore, your TDS reading will not change much unless you have a significant amount of heavy metals or sedimentary minerals in your water.

I understand that the media used within the fluoride reduction elements is activated alumina, it that the same thing as aluminum?

The media used to extract the fluoride and arsenic is activated alumina. Since fluoride is a by-product of aluminum production, fluoride has a natural affinity to recombine with activated alumina making it an ideal extraction media. We are not chemists but will communicate our understanding on the subject. Both nutritionist and lab technicians have informed us that aluminum and alumina are two separate animals. Aluminum can cross the blood brain barrier and cause problems with the brain whereas alumina is inert. It is our understanding that alumina is oxidized aluminum. Aluminum is regulated whereas alumina is not for example, alumina is the material used for making the paste in toothpaste. At any rate, when testing for aluminum in water, most tests cannot distinguish between aluminum ions and oxidized alumina. Since we are not chemists, we tested the effluent from the filters and included that information in our brochure. While we were not required to do so, we felt that it was important to disclose to our customers what our results were so that they would have the necessary information to do further research on the issue should they desire to do so. We think it was significant in the test we conducted using the combination of Black Berkey elements and PF-2 elements there was a net reduction in the tested aluminum content of the source water vs. the purified water. Again that test did not distinguish between aluminum and alumina. The bottom line is that the media utilized is oxidized alumina and not aluminum.

Viruses FAQ

I thought that to have a filter with pores fine enough to remove viruses, there should be frequent clogging problems. Is that why some used a bacteria size pore and a secondary disinfectant step (e.g., iodine resin) to kill viruses.

The proprietary filter formulation used in Black Berkey purification elements makes up for the incredibly small pore size by utilizing an exponentially greater number of micro pores in each purification element than that found in other filter elements. This is the reason Black Berkey purification elements produce approximately 8 times more water per hour than do other elements. Therefore, while some of the surface pores will clog up from contaminates, it is difficult for such contamination to overwhelm all of the pores and so clog up the filter. Eventually the majority of surface pores may clog up slowing down the flow rate of the Black Berkey purification elements. When this happens the filter can be refreshed by simply brushing the outside of the element with a ScotchBrite pad or toothbrush. This will remove the surface pores that have become clogged. Therefore, in answer to your question, even though the filters have such small micro fine pores, the element will not clog up prematurely.

How does your filter in the Berkey system deal with viruses? Possibly with a series of filters with graded pore sizes? Or is the virus filtration due to the tendency of viruses to clump with bacteria and debris in the water?

The micro fine pores are so small that they prevent micro fine particulate such as bacteria, virus and even food coloring particulate from passing through the tortuous path that water is able to pass through. These contaminates are trapped in the microfine pores while the much smaller h30 molecules are not. Therefore, in answer to your question, this method separates the contaminates from the purified water.

Is the MS2 - Fr Coliphage still known to be a good indicator of virus filtration? At least one article suggests that it might not be. Do you have tests on any other viruses?

MS2 and Fr Coliphage are two separate virus with two different removal characteristics. That is why they are used as surrogates for other types of virus. These virus were selected, by both the EPA and the Military, because of their small size relative to other virus strains and the difficulty in removing both strains. They each are approximates 24-26 nanometers in size which makes them among the smallest of virus. To see their relative size we would suggest that you visit The University of Utah Cell Size and Scale Chart. These virus are comparable in size on that chart to the Rhonivirus. Therefore, in answer to your question, yes MS2 and Fr Coliphage are the ideal virus for use as indicators of a purification systems ability to remove virus.

Special Notes:

To understand the difference between the size of path bacteria and viruses, we suggest the following web link as it will give you a great visual of the difference: The University of Utah Cell Size and Scale Chart.

Slide the scale at the bottom to see the size of virus vs bacteria vs other potential contaminates and magnify to greater levels.

The fact that Black Berkey purification elements have been tested to remove viruses to greater than the EPA purification standards suggests that contaminates larger in size, such as bacteria, should also be removed.

  • The MS-2 virus is 24-26 nm in size.
  • The Fr Coliphage virus is 25nm in size.
  • In other words, they are smaller than the hepatitis virus at 45mn and the rhinovirus at 30nm both referenced on the chart.

For more information on the MS-2 virus: MS-2 - Wikipedia

For more information on Bacteriophages in general: Bacteriophages: Update on application as models for viruses in water

Below please find links to independent test results of the black berkey filter elements.