Deal of the Week

Special Offer - Doulton / AquaCera Water Filters

Thursday, December 22, 2011, 5:27 PM

Back by popular demand, we are pleased to announce that St. Paul Mercantile is offering members a holiday season discount on 10% off its most popular stainless steel and plastic ceramic water filter systems plus free Shipping. This offer includes upgraded components these highly effective, highly dependable solutions that ensure your family will be able to create safely potable water under virtually any conditions.

Specifically, St Paul Mercantile is offering us:

  • 10% Off Complete Water Filter Systems, Replacement Filter Candles, and the Fluoride/Heavy Metal Reduction Add-On Filters.  
  • Free Shipping  (Continental USA Only)

Click here to take advantage of this offer, exclusive to readers.

AquaCera has just released an updated version of its 7" White Ceramic Candle Filter.  These updates include a finer ceramic with smaller pores that remove an even higher percentage of pathogens. They also use a new coconut husk-based activated carbon center that provides an increased level of removal for organic compounds in water.  To read more on the specifications of these filters click here

2011 gave us plenty of examples (from hurricanes and floods, to earthquakes and tsunamis) of why having a reliable method of water filtration is vitally important for both emergency situations and everyday healthy living.

For those who are looking for that last minute holiday gift or setting a new resolution to be a "healthier me" in 2012, this Special Offer from SPM will be a great way to give the gift of health to yourself and others.  

Here's the excerpt from our What Should I Do? guide that speaks to these water filters:

Clean, Clear, Potable Water

I have never yet had to worry about water availability because each place I've lived has had potable surface water nearby.  Our current house has a deep well, but I plan to invest in an additional shallow well by drilling down 80 to 90 feet to a water-holding gravel layer that sits under our land.  To this shallow well, we'll attach both a windmill (for relatively continuous pumping for gardening purposes) and a hand pump capable of drawing from that depth.  We will also be installing rainwater catchment systems to our gutters.

Clean and abundant water is critical for sustaining life, no matter what your standard of living.  Some lucky folks have natural springs, streams, or other bodies of water on their property, which can greatly ease the issue of water access in times of emergency.  But the emphasis here for everyone, even if you've got water right out your front door, is on cleanliness.  

So perhaps now you have stored water or have access to a natural source of water.  But how can you be certain that this water is safe to drink?  Fortunately, that's easy.

Our family uses a ceramic filter based on proven technology that can render even the most foul pond water into clean, pure drinking water.  It has no moving parts - you just pour water in and let gravity do the rest.  There's an upper reservoir with filters in it connected to a lower tank.

We happen to use the Doulton filter (more popularly known as the Big Berkey), which also is the filter that appears to be most preferred by members of the community:

Doulton Filter with Two 7-inch Ceramic Candles

  • Ceramic filters are extremely efficient at removing particulates and bacteria, and are very long-lasting.
  • Water filters through at approximately two quarts per hour.
  • Each 7" ceramic candle will filter 535 gallons each (replace candles yearly if using on a continual basis).

This filter removes all bacteria, all other little critters, and even a host of noxious chemicals.  We even use it to treat our otherwise perfectly safe well water right now, because it removes even slight impurities and improves the flavor.  But having this process be part of our daily life also gives us familiarity and practice in using this system of water filtration.

Knowing that our family will always have clean drinking water, no matter what economic or weather emergency may arise, adds to our resilience.  It also gives us a peace of mind that is invaluable.

We like the Doulton in the stainless steel model because it sits in our kitchen exposed to light.  If it were transparent, algae and other photosynthetic critters would eventually grow in the tank and shorten filter life by gumming them up.  Metal doesn't let the light through and thus keeps the water cleaner.

But the stainless model is a bit pricey (beginning at $178 + S&H), and some folks prefer to buy and stash a cheaper model to be pulled out only under emergency conditions.  If this is your plan, long-term algae growth is not a concern.

For infrequent emergency use, we recommend the Aqua Cera plastic water filter
with Doulton ceramic candles, which is currently priced at $128 + S&H.

  • Uses the exact same ceramic candle filters as the Doulton model.
  • Water filters through at approximately two quarts per hour – throughput can be materially increased by adding more ceramic candles (up to five).
  • Clear surface makes it easier to see how much water you’re using up as you go. 

We hope you continue to find these offers on essential resiliency items a welcome addition to the news and other articles on the site. We look forward to providing updates to the WSID Guide and Series in the coming year.  


Full disclosure: Based on our existing relationship with St. Paul Mercantile, will receive a small commission if you purchase through this special offer. This will not impact the price you pay (in fact,as the offer states, you're getting an exclusive price discount not available to the public-at-large). The proceeds we received will be immediately invested to fund new features and functionality for this site.

We’d also love to hear any feedback based on your first-hand experience with the products and vendors that we recommend through these special offers (and elsewhere on this site). Our goal is to ensure that we’re doing our utmost to offer the best guidance for utility, value, and service.

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Related content


stpaulmercantile's picture
Status: Bronze Member (Offline)
Joined: Nov 19 2008
Posts: 87
Also Price Match Guarantee

If you find a better offer on these water filters and replacement candles elsewhere, I will match the price, plus Chris will still receive a donation to support this website.


[email protected]

JAG's picture
Status: Diamond Member (Offline)
Joined: Oct 26 2008
Posts: 2492
Uniform Pore Size?


I've always been interested in these ceramic filters but I have some doubt about the <1 micron pore size that they typically claim for these fitlers. From what I understand, the process by which they make the candles does not give a uniform pore size. Are there any studies testing these filters that you can reference for me?

Also, how does the flouride/heavy metal filter work? Ion-exhange is the only method that I know that is effective for removing heavy metals from water.

Thanks for your time and feedback....Jeff

jrf29's picture
Status: Gold Member (Offline)
Joined: Apr 18 2008
Posts: 453
Re: Uniform pore size
JAG wrote:

I have some doubt about the <1 micron pore size that they typically claim for these fitlers. From what I understand, the process by which they make the candles does not give a uniform pore size. Are there any studies testing these filters that you can reference for me?

The CDC and WHO have done tests on ceramic filters for use in disater-stricken areas and in Third World countries.  The effectiveness depends entirely on the production quality of the filter.  Although tests have found that even filters produced locally by potters in Third World countries can attain relatively high levels of effectiveness at bacterial removal.  Industrially manufactured filters using diatomaceous earth clays can achieve extremely high levels of effeciveness.

Of course the pore size of clay filters is never uniform.  It is non-uniform by nature, but that is OK because it relies on depth filtration as opposed to membrane filtration.  Water must pass through a thickness of clay that achieves very high filtration efficiency over the thicknesses involved. 

In depth filtration we would expect to see is a gradual increase in effectiveness as particle size increases.  At the particle size for which effectiveness approaches 100%, you can say that the filter has a pore size equivalent of whatever.  Actually, it looks like Doulton has some data on their site:

Doulton wrote:

    * >99.99% E.coli removal
    * Tested with live Cryptosporidium cyst to 100% removal far exceeding EPA three log cyst reduction requirements
    * 100% efficiency at 0.9 µm absolute (0.5 µm absolute ANSI standard)
    * > 98% efficiency at 0.2 µm
    * > 90% efficiency at 0.05 µm
    * < 0.07 NTU turbidity reduction

Right . . . the filter begins to achieve practical 100% efficiency for particles of 0.9 microns, so it has an effective "pore size" around 1 micron.  That is, the equivalent of a single membrane with that pore size.

Since the performace of any given ceramic filter will depend entirely on the manufacturing processes of the filter in question, every manufacturer must prove the performance of their filter.  It appears that Doulton has performed many tests on their filters, and the results are impressive.  After a few minutes of looking, I found these links to tests (links to more tests can be found on the pages):

JAG wrote:

Also, how does the flouride/heavy metal filter work? Ion-exhange is the only method that I know that is effective for removing heavy metals from water.

I've never heard of activated charcoal removing metal ions.  But according to the website, it appears that at least one of their filter types (but not the Sterasyl) incorporates an ion exchange medium in the interior of the filter "candle." 

As for the silver impregantion, at least one study found that impregnation of filter elements with silver did not do anything to increase efficiency at microbial reduction.  This seems about right, since the water probably isn't in contact with the silver long enough.  Although theoretically, the silver would prevent bacterial colonization of the filter elements and possible resultant clogging.

stpaulmercantile's picture
Status: Bronze Member (Offline)
Joined: Nov 19 2008
Posts: 87
Pore Size and reason for Silver in the Clay


 The explanation already given regarding pore size is excellent.  I have recently switched to Aqua Cera brand of candles, as their specs are even better.  Here is what the test results for the Aqua Cera candles say:

Here is the entire document:

 Here is the portion of the document regarding pore size:


The majority of pathogenic (disease causing) bacteria and cysts
are larger than one micron. The pore size of the filter element is
controlled so that it will remove all suspended matter larger
than 0.3 microns.
Pathogenic bacteria
Cholera, Typhoid, Salmonella, Serratia, Fecal Coliform >99.99%
E. coli - 100%
Cryptosporidium Parvum, Giardia Lamblia - 100% removal
Down to 0.8 micron - 100%
0.3 - 0.5 micron >99.99%
Turbidity >99.7%
Organic Chemicals
Pesticides, herbicides and organic solvents
Iron, Aluminum
Taste & Color
Hydrogen Sulphide, Iron, etc.

SILVER - the purpose of the silver particles in the clay is to create a toxic environment for trapped bacteria so they cannot reproduce on the ceramic surface.  Without the silver, the bacteria would multiply and eventually grow through the filter.



JAG's picture
Status: Diamond Member (Offline)
Joined: Oct 26 2008
Posts: 2492

Thanks for the feedback guys....I'll get busy reading now.


carolynraye's picture
Status: Member (Offline)
Joined: Jul 16 2009
Posts: 14
Thanks for making this offer available again!

I missed it last time due to my own fence-riding.... thanks for including the links to the FAQ and specs... that's what pushed me over the edge and made me actually bust out the CC. Thrilled to see the offer again!

LG's picture
Status: Bronze Member (Offline)
Joined: Oct 6 2009
Posts: 59
Gravity Flow Water Filters


My wife and I used a Katadyn Gravidyn gravity flow water filter in rural Alaska for many years. We have always been happy with the results. We chose the plastic version because it was easier to mail from one village to another. I highly recommend this type of filter for either remote use or everyday use. At this time, there is one sitting on my kitchen counter. It makes my feel better knowing that my water has been filtered.

I recently purchased one of your Sun Ovens and am very happy with the quality of the product.




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