Engineered on decades of water science

Water is your most
frequent input.

So audit it like one. What is already in Europe’s tap water, the peer-reviewed RO literature with PubMed IDs, and exactly what we will and will not claim.

New on the list.
Already in the water.

The EU only made PFAS a limit at the tap in January 2026, and lead pipes get until 2036 to meet the lower lead limit. The rules are catching up with what is already in the system.

34/36tap water samples from 11 EU countries contained TFA, a short-chain PFAS, in independent 2024 testing.

1 in 2samples were above the EU’s 500 ng/l “PFAS Total” value if TFA is counted.

Sources: PAN Europe, 2024 (NGO testing); Directive (EU) 2020/2184, Annex I.

SubstanceEU limitTest water inOsmosis One out

Lead10 µg/l, 5 by 20361520.3
Arsenic10 µg/l298<0.2
Cadmium5 µg/l51<0.2
Chromium50 µg/l, 25 by 2036274<1
PFOSin Sum of PFAS, 0.10 µg/l1.0<0.004
PFOAin Sum of PFAS, 0.10 µg/l0.73<0.004

µg/l. Nord’s published test, where incoming water held these substances at many times the EU limit. Test values, not a guarantee for every source water. TFA was not part of the published test.

What the literature says about RO.

Peer-reviewed, mostly US EPA and WHO-linked work. Every number links to its source. None of these studies tested Osmosis One; they tested the method. Our own unit has its 16 published results.

PFAS2 of 3
under-sink RO units in US EPA testing kept all six PFAS below detection for the entire run. In the same test, carbon-only columns broke through after about two hours of run time.
Patterson et al., AWWA Water Science, 2019 PMID 31338490
PFAS, in real homes73
homes tested in North Carolina. Under-sink RO showed near complete PFAS removal. Typical carbon filters took out roughly 60 to 70% of long-chain PFAS.
Herkert et al., Environ. Sci. Technol. Lett., 2020 DOI
Arsenic and nitrate>99%
rejection, mostly, across nine point-of-use RO units installed in homes in a US EPA programme. Uranium and antimony too.
Chen et al., Water Research, 2020 PMID 31958595
Viruses4.9 log
average virus removal for RO, from a 165-article systematic review commissioned for the WHO drinking-water guidelines. Membranes overall: 5.7 log for protozoa.
Burke et al., Environ. Sci. Technol., 2025 PMID 40152626
Microplastics93%
of microplastics removed at a full-scale plant, where the UF and RO line beat ozone plus carbon. No household RO study exists yet, so this is the honest ceiling.
Dalmau-Soler et al., Environ. Sci. Pollut. Res., 2021 PMID 33709311
The catch1 of 3
household RO units in an older study actually met the arsenic standard. The technology is not the guarantee. The unit is. That is why we publish ours.
Lin et al., 2002 PMID 12164638

A national food agency points to RO.

In its guide to reading a water analysis, Sweden’s food agency Livsmedelsverket names a reverse osmosis unit at the kitchen tap as one option when these show up in your water:

PFAS
Fluoride
Cadmium
Mercury
Radon

Source: Livsmedelsverket, Dricksvattenanalys. It describes the method, not a specific product.

Which method stops what.

The CDC’s own comparison of home water treatment. Osmosis One combines two of these methods: reverse osmosis, which also removes chemicals such as lead, copper and chromium, and UV after pre-filtration.

Method	Parasites	Bacteria	Viruses	Chemicals
Microfiltrationabout 0.1 micron	Removes	Somewhat	Does not remove	No
Ultrafiltrationabout 0.01 micron	Removes	Removes	Somewhat	No
Nanofiltrationabout 0.001 micron	Removes	Removes	Removes	Some
Reverse osmosisabout 0.0001 micronIn Osmosis One	Removes	Removes	Removes	Lead, copper, chromium and more
UV, after pre-filtrationlight, not a filterIn Osmosis One	Removes	Removes	Removes	No

Removes Somewhat Does not remove. Source: CDC, About home water treatment systems (2024). Method-level guidance, not a test of Osmosis One.

Strip. Restore.
Protect.

Two 2-in-1 cartridges and UV-C. The first strips with an RO membrane and carbon. The second puts minerals back and polishes with carbon. UV-C protects last. All included.

Cartridge 1, 2-in-1: RO + carbon

Strip.

RO membrane and carbon filtration in one cartridge. See the published results for lead, arsenic, PFAS and more below.

Cartridge 2, 2-in-1: minerals + post-carbon

Restore.

Calcium, magnesium and potassium go back in after RO, and a final carbon stage polishes the taste.

UV-C, the last step

Protect. For bacteria, viruses and parasites.

After RO and the mineral post-filter, the water passes UV-C light last. A second barrier against bacteria, viruses and parasites, working with light instead of size.

Illustrations of the processes, not technical cross-sections. Go deeper into the science.

Too big
to get through.

Parasites like Giardia and Cryptosporidium are measured in microns. An RO membrane’s pores are about 0.0001 micron. By size alone, there is no way through. Then UV-C follows as a second barrier.

42,000×Cryptosporidium, the smaller of the two, is roughly 42,000 times wider than an RO pore.

≈27,000people in Östersund were affected when Cryptosporidium got into the town’s drinking water in November 2010.

Size, in micronsLog scale. Each step is ten times smaller.

Giardia cyst8-19 µm
Cryptosporidium oocyst4.2-5.4 µm
Typical microfilter poreabout 0.1 µm
RO membrane poreabout 0.0001 µm

Sizes from the CDC (Giardia, Cryptosporidium, home water treatment), which lists reverse osmosis as removing parasites, bacteria and viruses. This is a size comparison, not a parasite test of Osmosis One. Nord’s published results include total coliform bacteria: 5.0×10⁵ to <1 CFU/100 mL. Östersund figures: Widerström et al., Emerging Infectious Diseases, 2014.

Why UV-C goes last.

Stored water is where bacteria come back. A classic study of 300 household RO tanks found most of them holding 10,000 to 100,000 bacteria per millilitre PMID 2611732. So the tank in Osmosis One lifts out for cleaning, and UV-C sits after everything else.

UV-C is dose-dependent. Parasites go down at very low doses; viruses need far more. We have not published a validated dose for our UV-C stage yet, so we do not put a log number on it. When we have one, it goes here.

UV dose needed, from the literature

Giardia>4 logat about 1 mJ/cm²PMID 12075814
Cryptosporidium≥4 logat 10 mJ/cm²PMID 32313290
Viruses4 logneeds up to 186 mJ/cm²US EPA, 40 CFR 141.720

Why we put minerals back.

RO water is close to empty. The WHO’s Nutrients in Drinking Water (Kozíšek, 2005) describes demineralised water as highly aggressive: it pulls minerals from whatever it touches, including food while you cook.

10mg/lMinimum magnesium the WHO chapter’s author suggests for drinking water. 20 mg/l for calcium.
12EU countries regulate calcium, magnesium or hardness in drinking water by law PMID 32007436.
7.5-8.5pH after One Mineral Restore, per Nord’s specification. Calcium, magnesium and potassium go back in.

We add minerals for balance and taste. We do not claim a health effect from the water, and the mineral content depends on your source water and filter age.

The Reddit questions,
answered.

We read the threads in r/WaterTreatment, r/Biohackers and r/PFAS. These are the objections that come up most, answered without hype. Test, don’t guess.

“RO water is dead water.”
It is empty, not dead. RO takes minerals out along with everything else, and most of your minerals come from food anyway. We put calcium, magnesium and potassium back for taste, balance and pH, not as a supplement.
“RO water is acidic.”
Fair. Pure permeate picks up CO₂ from the air and settles near pH 6, with nothing to buffer it. That is exactly why One Mineral Restore sits after the membrane: per Nord’s specification it brings the water to pH 7.5 to 8.5.
“Remineralisers are a gimmick.”
Often a fair hit: many are a bit of calcite with no numbers. Ours exists for taste and stability, and we are not hiding behind adjectives. The mg/l figures come from a lab, and when we have them, they go on this page.
“Low TDS is dangerous.” / “TDS is meaningless.”
Neither. TDS is a trend number, not a safety score. It cannot see PFAS, lead or bacteria. Use the display to spot membrane wear over time, and use a lab test for specific substances.
“RO wastes a ton of water.”
Osmosis One’s published ratio is 3.5 litres of filtered water per litre of concentrate. Use the concentrate for plants or cleaning. Never filter it again: it holds what the membrane rejected.
“No RO removes 100%.”
Correct, and we do not claim it. Our published results show 99.80% for lead, over 99.93% for arsenic, over 99.60% for PFOS, and 94.78% for fluoride, the lowest of the sixteen. Unit quality matters, which is why we publish ours.
“Tanks grow bacteria.”
They can. A study of 300 household RO tanks found most holding 10,000 to 100,000 bacteria per millilitre. Our feed tank lifts out so you can actually wash it, and UV-C is the last step before the pitcher.
“My tap water is fine.”
Most of the time in Europe, it is. Östersund and the Veneto region were fine too, until they were not. Test first if you want certainty, and read the result against the EU limits above, not against a marketing claim.

Three kinds of evidence.
Three different scopes.

Applies to: this system
A product test
Measures an identified system, filter and contaminant under stated conditions. Product-specific reduction claims belong here, like the 16 published results.
Applies to: one component
A component certificate
Covers the listed component and scope. A certified membrane does not make the complete appliance certified. .
Applies to: the technology
A scientific study
Explores a treatment technology or a health association. It gives context, but does not certify any particular water system.

The research library.

Fifteen studies behind the questions people ask about water. Open an entry for its context and limits.

15 entries

ContaminantsMicroplastics in arterial plaqueMarfella et al., New England Journal of Medicine, 2024

A clinical observational study of the association between plastics detected in arterial plaque and later cardiovascular outcomes.