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In a nutshell, Doulton/Berkefeld ceramic water filters remove bacteria from water, making it safe to drink. They do it the
same way nature does, by using gravity to move water through tiny pores of crushed fossils - pores that are big enough for
water molecules to get through, but too small to allow bacteria and water-borne pathogens to pass. The technology has been
in use since the early 1800s and is the filtering method of choice by missionaries and relief organizations all over the world.
- What is the history of Doulton/Berkefeld Water Filters?
John Doulton founded his first pottery in 1815. As early as 1827, Henry Doulton developed ceramic filters for removing bacteria from drinking water. The Thames river was heavily contaminated with raw sewage; cholera and typhoid epidemics were rampant.
In 1835, Queen Victoria commissioned Doulton to produce a water filter for the Royal household. Doulton created a gravity fed filtration system that used a ceramic filter.
With Pasteur's advancement in microbiology, Doulton's Research and Development department created micro-porous ceramic cartridges capable of removing bacteria with better than 99% efficiency.
Today, Doulton ceramics are used in over 150 countries. In 1985, the British Berkefeld brand was acquired by
Doulton Industrial Products, the manufacturer of Doulton water filters. Today, the Doulton and British Berkefeld names are
the preferred choice for water purification products in worldwide locations where outbreaks of illness are associated with
unreliable water supplies. These water filters have truly stood the test of time.
- How does the system work?
Just add water into the upper chamber. Gravity causes the water to flow through the filters to the lower
chamber. A four-filter system using 7" filters will produce about a gallon per hour. Using four 9" filters will
produce about 1.25 gallons per hour.
- What is the technology behind the filter elements and why are they so special?
A) Doulton invented the ceramic filter for water filtration in 1827.
B) The ceramic filters are called "candles". They are made from crushed diatomaceous earth that is liquified,
formed, then baked in a kiln.
C) Water molecules slowly work their way through the ceramic to the hollow center of the candle, then the water drips
into the lower compartment of the filter. Sediment, bacteria and other micro-organisms are too large, so are
trapped by the ceramic in the upper compartment of the filter.
D) The ceramic contains tiny grains of silver, which is toxic to bacteria. The silver prevents the captured bacteria from
reproducing on the filter (unlike paper filters that provide an excellent growth medium). The silver also prevents
Mitosis or Grow-Through, a condition that makes filters made from paper and plastic unusable after a short time.
E) Pore size: less than 1 micron
F) Removes >99.99% of Cryptosporidium, Giardia, E. Coli, Vibro Cholerae, Salmonella, Dysenteria.
G) The center of the ceramic filters is filled with GAC (granular activated carbon). Carbon removes bad tastes
and odors as well as pesticides, herbicides, organic solvents, trihalomethanes.
H) Ceramic elements last much longer than paper filters because they can be cleaned 50 to 100 times or more. See below.
- What are some of the water sources I can use?
Water from ponds, creeks, lakes, rivers, wells, cisterns, rain, or even water you have stored yourself can be used for drinking and cooking with peace of mind.
- Water Production Rate
The rate of water production depends upon 1) the number of ceramic candles, 2) the size of the candles, and
3) whether the candles are clean or starting to get clogged. Doulton/Berkefeld stainless steel filters can be equipped
with either two or four candles, and the candles can either be 7" or 9" long. More (or longer) candles just means
there is more surface area, so the water filters through faster.
With two 7" candles, you will get about 2 quarts per hour. Four 7" will provide about 4 quarts per hour. If you
use 9" candles, you'll see a slight improvement in filtering speed, but once the water level drops 2 inches, there will be
no difference in filtering speed between the 7" model or 9" model.
- Stainless Steel or Plastic Body?
Doulton/Berkefeld filters have traditionally been made of stainless steel. The bodies are made in India, then
shipped to London where they are packaged and the ceramic filters are added. This is what makes the stainless
option a bit pricey.
In 2008, Doulton USA introduced the American Berkefeld, which is a plastic-body filter, made in the USA. It is
packaged with genuine ceramic filters from the factory in London. The American Berkefeld is larger than the
stainless steel model, and it can be fitted with 2, 4 or 5 ceramic filters. It will also accomodate the larger 10"
ceramic filters in addition to the 7" and 9" that fit the stainless model.
- Can I Make My Own Filter?
Absolutely. St. Paul Mercantile offers Bucket Filter Kits that include two or four filters, plus a spigot.
You provide two buckets (2.5 gallon, 5 gallon, any size). This is the most cost-effective way to go. Detailed
instructions can be downloaded here:
Click Here to Download Bucket Filter Instructions
- How Many Gallons of Water Will One Ceramic Candle Produce?
This requires some explanation. The manufacturer recommends replacing 7" ceramic candles after 535 gallons, and 9" candles
after 700 gallons. So if you had a filter containing two 7" candles, the manufacturer recommendation would be to
replace the candles after filtering 1070 gallons. If you pay about $60 for two 7" candles, you are getting
about 18 gallons of clean water per dollar.
The primary reason that Doulton recommends replacing filters at that many gallons is that the granular carbon
at the center of the candles ceases to be effective at about that point. If your primary use of the filter is to
remove bacteria, however, the ceramic will continue to do that for a very long time. It is not uncommon for people to
continue to use the ceramic candles for many years, cleaning them only 1-2 times per year. The candles can be cleaned
at least 50-100 times, so you do the math.
If you are depending upon the carbon center to remove chemicals or odors, you should replace the candles more
frequently. Or, you can purchase an inexpensive charcoal filter (a coffee strainer and bag of granular activated carbon
are sufficient) and use the charcoal as either a pre- or post-filter.
- When do I clean the ceramic filter element?
When the time it takes for the water to filter into the lower chamber decreases to the point where it is no longer meeting your daily water needs.
- How do I clean the filter element?
Hold the ceramic element under clean running water while scrubbing lightly with a 3M ScotchBrite pad or
toothbrush. Cleaning should be performed evenly, working from the threaded end down. The cleaning process
removes the outermost clogged ceramic pores from the candle, therby exposing a fresh unclogged surface.
- How do I determine when the filter elements must be replaced?
The ceramic element will become slightly smaller from repeated cleanings. Eventually, the ceramic wall will wear thin and crack. Once a crack occurs, the integrity of the filter has been lost and it must be replaced.
- How do I determine when the granular carbon in the ceramic element is exhausted?
When bad taste and odor of the source water is no longer removed. The ceramic shell will continue to
remove pathogenic bacteria even after the carbon is exhausted. If your water tastes bad, you may continue
to use your Doulton/Berkefeld to remove bacteria, and either pre-filter or post-filter the water with
an inexpensive carbon filter, such as a Brita.
- Is it possible to reactivate or regenerate the granular carbon in the filter element once it becomes saturated with chemicals?
Sometimes. Some chemicals such as chlorine can be removed from the carbon by simply boiling the ceramic filter element in water for five minutes. Note: To avoid cracking the ceramic shell, place the element in cool water and then bring the water to a boil. Never place a cool element in boiling water or a hot element in cool water.
- Can I prolong the need for cleaning the filter elements?
Yes. You can pre-filter the water through a coffee filter before pouring the water into the Berkefeld. However, this is not necessary for proper functioning.
- How does the Doulton/Berkefeld compare to other types of water filtration systems?
A) Inline Systems: useless if you do not have water pressure
B) Hand Pump Units: great for camping, but hard to pump. Not practical for long term emergencies. Short life span.
C) Resin or Carbon-based gravity filters: short life span, typically 250 to 1000 gallons.
D) Ceramic-based Gravity Filters: no water pressure required, long life span of elements.
- Who uses the Doulton/Berkefeld Emergency Filters?
A) Relief Organizations like the Red Cross, Unicef and the Peace Corps. 58,000 units were used in Sarajevo
after their water treatment plant was destroyed by the Serbs. In 1998, thousands of units were shipped
to relief organizations in Honduras.
B) Missionaries all over the world (more than 140 countries) have used ceramic filters for many decades.
C) Populations in third world countries where water supplies are frequently contaminated.
D) Churches and non-profit agencies frequently have water projects all over the world. St. Paul Mercantile assists
in these projects by providing ceramic filters at cost.
- What types of bacteria are removed or reduced?
Pathogenic bacteria, such as Cholera, Typhoid, Salmonella, Serratia, E.Coli, and Fecal Coliform are removed >99.99%.
Cysts, such as Cryptosporidium Parvum and Giardia Lamblia - 100% removal (based on tests by Arizona State University)
Sediment: 100% removed down to 0.9 micron, >99.999% removed 0.5-0.8 microns (based on tests by Spectrum Laboratories, Minneapolis, MN)
Organic Chemicals, such as pesticides, herbicides, organic solvents and trihalamethanes are reduced.
Chemicals, such as chlorine, are reduced.