Filtration, explained
Everything we know about filters, and everything we don’t.
Aurmina binds contaminants and drops them out of the water. Something still has to separate what you drink from what settled — and that something is a filter. Decanting carefully into a second container will get you part of the way, but a filter is what does it reliably.
So filtration is part of using this product.
If all you want is a filter recommendation, it is right here. If you want to know how your own filter does, and how it compares, the rest of this page is for you.
Our recommendation is one particular filter: a 0.2 micron ceramic element made by Korea Ceramics. It is the element every contaminant figure on this site was produced with, it has a history with Shimanishi going back decades, and we sell it. It is a standard ceramic dome, so it drops into most gravity housings built for one — three that take it are listed just below.
Compatible gravity systems
Widely available vessels that accept a standard ceramic dome. We have not tested them, we earn nothing from them, and this is not an endorsement of the filters they ship with — it is simply a list of what fits.
Already have a filter? Here is what it does well, what it does not, and what changes when you treat with Aurmina first.
No single method of treating or filtering water produces a uniformly acceptable result. Every approach involves trade-offs among cost, energy requirements, contaminant-removal performance, water wasted, health benefits, and health risks. The first question to ask of any method is what the filter removes, and what it allows to pass through.
On our filter comparison page you can find the system you use, see which categories of contaminant it removes and which it does not, and see what pre-treating the water with Aurmina before filtering adds to its performance. Aurmina alone, without filtering, decreases the number of categories by more than half, while for nearly every filter system except reverse osmosis or distillation, pre-treatment further increases the number of categories removed.
If you do not like what you learn — if the gap that remains is one that matters to you — that same page sets out the highest-performing arrangements we know of, how each pairs with Aurmina, and what each one costs you in minerals, in water sent to the drain, in electricity and in money. No configuration wins on all four. We would rather show you the trade than sell you a winner.
Treat with Aurmina first. Then pour into your filter second.
- Dose your water with Aurmina in a separate clean vessel — a pitcher, jar or carafe.
- Let it stand 24 to 48 hours, undisturbed.
- Pour the clear water off the top into your filter — the one you already own, or ours.
- Rinse the treatment vessel, refill, redose.
- Drink and cook from your filter’s spigot.
Never add Aurmina into the top of your filter system itself. A gravity system starts draining the moment you fill it, so the water never sits still long enough for the minerals to finish their work — and the half-formed floc blinds the element and shortens its life. The chemistry needs a still container; the filter needs water that has already cleared.
The one we stand behind
A 0.2 micron ceramic element, and why this one.
Everything above is general. This is specific, and it is the only filter recommendation on this site.
Ceramic domes look alike. They are not alike. Effective pore size is the product of a long chain of manufacturing decisions: the ceramic body itself, particle-size distribution, moulding pressure, wall thickness, how the element is dried, the temperature it is fired at, and how tightly all of that is held from one batch to the next. Get any of it wrong and the number printed on the box stops describing the object in your hands.
The failure modes are physical and unglamorous. A microscopic crack, an irregular pore, or a poor seal where the element meets its mounting stem lets water travel around the barrier rather than through it. Push density the other way and flow slows to something nobody will live with. Two elements can carry the same 0.2 micron rating and behave nothing alike, which is why we name a particular element rather than a category.
Every contaminant reduction test we have performed was done with a 0.2 micron ceramic gravity element made by Korea Ceramics. Not a class of filter. That element. When we say 147 analytes were driven below detection, this is the thing the water passed through on its way to the laboratory.
Those tests ran with 24 hours of contact time and nothing else in the path — no carbon stage, no ion exchange, no redox medium. The mineral chemistry and a ceramic element, and that is all.
Three implications follow from that. First, the results are not achieved by the filter alone: a ceramic element removes nothing dissolved, so whatever left the water was taken out as a result of the flocculating chemistry. Second, the reductions are a floor rather than a ceiling — time-series testing shows reductions still climbing at 48 hours. Third, adding a carbon filter in series would bring a second mechanism to bear on the dissolved organics the ceramic cannot touch — and the gravity housings we list above include a carbon stage as well as a ceramic dome, all of them compatible with the element we sell.
Shimanishi Kaken, Matt Bakos and Dr. Kory each have their own history with Korea Ceramics. Bakos has imported Themarox into North America for twenty years and bought their elements directly for much of it. Dr. Kory’s history is the shortest and the plainest: their element has run in his own house for the past year and a half, across a good number of them, and he trusts it enough to put his name on this page.
Korea Ceramics was later acquired by Outriger, and the element now ships almost exclusively within Korea. We found one importer bringing it into the United States, bought their entire current inventory, and we sell it here. You should factor that in. We are not telling you it outperforms other ceramic elements — we have not tested other ceramic elements. We are telling you it is the one our results were produced with, the one with the older connection to this chemistry, and the one we run at home.
What this recommendation is not. It is not a finding about anyone else’s filter. We have not compared ceramic elements against one another, and we have not tested filter combinations. This element is recommended on provenance, history and daily use — three things we can account for — and not on a comparison, because we have not run one. When we run one, it will be published here whichever way it goes.
What we don’t know yet
The questions we haven’t answered, stated openly.
These are the gaps in our own data. We would rather you read them here than discover them later.
Comparisons we have not run
We have not tested what extra purity a ceramic-plus-carbon combination produces, so we are not going to put a number on it — though on the mechanisms involved it is likely higher than the ceramic gravity filter alone. Which is probably why a good many of our customers already run a carbon stage below the ceramic.
We have not tested ceramic elements against one another, and we have not tested filter combinations. We use gravity systems ourselves and we like them — no electricity, no plumbing, nothing sent to the drain, and a replacement schedule measured in years rather than months — but liking something and having tested it against the alternatives are two different things. When we run that comparison, it will be published with the data behind it.
PFAS
We have not tested Aurmina against PFAS and we make no claim about it. Third-party testing of this mineral chemistry did not show meaningful performance, and we would rather say so. PFAS removal is an adsorption problem, which means it belongs to activated carbon — and EPA reports carbon works well on long-chain compounds such as PFOA and PFOS, and less well on short-chain ones. A ceramic element alone, however fine, will not address PFAS at all.
Microplastics
Not yet tested. We have tried, and the analytical logistics have so far defeated us. Microplastics are found not only in bottled water but throughout the wider water environment: rivers, reservoirs, groundwater, treated municipal water and household tap water. Studies generally report higher particle counts in bottled water than in tap water, though results vary enormously because laboratories use different collection methods, detection limits and definitions. In bottled water some particles may originate in the source water, while others may be introduced by bottling equipment, filtration membranes, the bottle itself, or repeated opening and closing of the cap.
Using the common convention, microplastics range from roughly 1 µm to 5 mm; particles smaller than 1 µm are generally called nanoplastics. A 0.2 µm ceramic element is therefore, in principle, fine enough to retain conventional microplastics by size. That mechanical expectation is not the same as a measured or certified removal claim. Nanoplastics are a separate problem, and they are dealt with below.
The health significance remains unsettled. Smaller particles are of particular scientific interest because their size may make biological uptake more plausible, but current evidence does not establish the human-health risk posed by the concentrations ordinarily encountered in drinking water. Until we have tested the complete system using an appropriate, validated method, we are not going to claim a microplastic or nanoplastic reduction we have not measured.
Nanoplastics
Everyone says microplastics. Almost nobody says nanoplastics, and nanoplastics are the harder problem. Microplastics are a micron and larger, which means any ceramic element stops them — they are the easiest thing on this page to catch. Nanoplastics are smaller than that, and when researchers at Columbia examined three brands of American bottled water with a method that could see down to 100 nanometres, they counted an average of 240,000 plastic fragments per litre, roughly 90 percent of them nanoplastics rather than microplastics — ten to a hundred times more than earlier estimates, which had missed them because the instruments could not see that small. Proceedings of the National Academy of Sciences, January 2024.
Our own element is rated at 0.2 microns, which is 200 nanometres. It stops the coarse end of that range and passes everything finer. We have not tested Aurmina against nanoplastics and we do not know whether the coagulation binds them. Of every arrangement on our comparison page, nanoplastics are cleared by exactly two: reverse osmosis and distillation. Every other arrangement on this page, including ours, leaves them in.
What a micron rating does not tell you
A micron rating describes pore size, not performance against chemistry. A 0.2 µm element will stop a bacterium and pass a dissolved pesticide molecule without noticing it.
The long version
Want to compare every filter against every other?
We built a table of fifteen contaminant categories across ten arrangements — pitchers, ceramic, carbon, ultrafiltration, zero-TDS, reverse osmosis, distillation — each shown with and without Aurmina, alongside what each one costs you in minerals, in water sent to the drain, in electricity and in money. It is more detail than most people need, which is why it has its own page.
Other approaches
What we make of the rest of the water aisle.
Beyond filtration there is a whole aisle of machines and additives that promise to change your water — magnetised water, far-infrared and “energising” attachments, electrolysis ionisers, hydrogen generators, structured and clustered water. People ask us about all of them. We have written down what we think of each, including the one or two with real science behind them and the several with none, and we have kept it off this page because it is a different argument.
We will keep this page current.
When the testing is done, the results land here — including the ones that do not flatter us.