Measurlabs · ISO/IEC 17025

Our laboratory test results, substance by substance

More than 300 substances were tested on the Puure Nano cartridge by independent ISO/IEC 17025 accredited laboratories, coordinated by Measurlabs (reports 25146, issued 07/08/2026, and 30494, issued 31/08/2026). This page reproduces every result as it appears in the reports, including the less flattering ones. Values preceded by "<" are below the laboratory's quantification limit: the substance was no longer measurable.

View full report

How we tested

In 2026 we handed our Puure Nano cartridge to Measurlabs, a Finnish testing company that routes each analysis to an ISO/IEC 17025 accredited laboratory (DAkkS in Germany for PFAS, pesticides and pharmaceuticals; HAA in Croatia for microplastics, chlorine and fluoride). We wanted a simple answer to a simple question: what is left in the water once it has passed through the cartridge?

The protocol is the most demanding one there is for a filter. Pure water is deliberately loaded with a known dose of each substance, then driven through the cartridge at a pressure close to a household tap (Seaflow pump, 2.4 bar maximum). The water that comes out is analysed by chromatography and spectrometry, with quantification limits down to a billionth of a gram per litre. For microplastics and chlorine, the laboratory even built a custom seal and set up a water column of about 1.5 metres to reproduce mains pressure.

More than 260 parameters were measured: 20 PFAS, 157 pesticides, 24 pharmaceutical residues, some thirty metals and elements, microplastics, chlorine, fluoride, PAHs, bisphenols and phthalates. Every value below comes from a signed, numbered report (25146 parts A and B, 30494), downloadable at the bottom of this page. The methods are detailed on the methodology page.

Protocol: pure water spiked at a known concentration of each substance, driven through the cartridge by a Seaflow pump (max 2.4 bar), then analysed using standardised methods. Full detail on the methodology page.

PFAS, the "forever chemicals" (20 compounds)

Water spiked at 0.05 µg/L per compound (1.0 µg/L in total, ten times the EU regulatory limit of 0.1 µg/L). After filtration, none of the 20 compounds was quantifiable and the PFAS sum is below 0.010 µg/L, a reduction of at least 99% of the sum. Method DIN EN 17892, accredited for drinking water.

Heavy metals and undesirable elements

Tap water spiked at 10 µg/L per element, ICP-OES analysis accredited for drinking water. The percentage is the one calculated by the laboratory on the spiked water.

Minerals and electrolytes: preserved

Unlike reverse osmosis, Puure filtration lets the water's natural minerals through. Measured in the same test run.

Microplastics

Method ISO/DIS 16094-2:2023, FT-IR microscopy. Two one-litre samples of deionised water received 150 polystyrene microspheres of 70 µm. The unfiltered sample contained 112 at analysis (method recovery rate: 74.7%). After passing through the cartridge: no particles detected.

Pharmaceutical residues (24 substances)

Water spiked at 0.25 µg/L per substance, LC-MS/MS analysis. After filtration, only two substances remained quantifiable: metformin at 0.0088 µg/L (96.5% reduction) and sulfamethoxazole at 0.0027 µg/L (98.9% reduction). All others were below the quantification limit.

See all 24 detailed results

Substance	After filtration (µg/L)
Metformin	0.0088
Sulfamethoxazole	0.0027
Estrone (E1)	< 0.0025
17-beta-Estradiol (E2)	< 0.010
17-alpha-Ethinylestradiol (EE2)	< 0.010
Clarithromycin	< 0.0025
Erythromycin	< 0.0025
Roxithromycin	< 0.0025
Sulfamethazine	< 0.0025
Trimethoprim	< 0.0025
Diclofenac	< 0.010
Ibuprofen	< 0.100
Carbamazepine	< 0.0025
Amisulpride	< 0.010
Benzotriazole	< 0.010
Candesartan	< 0.010
Citalopram	< 0.010
Hydrochlorothiazide	< 0.010
Irbesartan	< 0.010
Metoprolol	< 0.010
4-Methylbenzotriazole + 5-methyl-benzotriazole	< 0.010
Telmisartan	< 0.010
Venlafaxine	< 0.010
Naproxen	< 0.10
Phenytoin	< 0.010
Nonylphenol	< 0.10

Pesticides and metabolites (157 substances)

Water spiked at 0.1 µg/L per substance, method DIN 38407-36, accredited for drinking water. After filtration, all 157 substances were below the quantification limit (less than 0.025 µg/L for nearly all, including atrazine, simazine, diuron, imidacloprid and metolachlor). The full list of 157 analytes is in the downloadable PDF report below.

PAHs, bisphenols and phthalates

The 7 PAHs (including benzo(a)pyrene), spiked at 0.1 µg/L, all come out below the quantification limit, with a sum below 0.004 µg/L. The 5 bisphenols (including bisphenol A), spiked at 0.25 µg/L, all come out below 0.047 µg/L. Of the 10 phthalates spiked at 0.01 µg/L each, the sum drops from 0.1 to 0.0152 µg/L (85% reduction); two remain quantifiable (diethyl 0.0085 and dimethyl 0.0067 µg/L).

See PAH, bisphenol and phthalate detail

Substance	After filtration
Benzo(a)pyrene	< 0.0012 µg/L
Benzo(b)fluoranthene	< 0.0016 µg/L
Benzo(k)fluoranthene	< 0.0016 µg/L
Benzo(ghi)perylene	< 0.002 µg/L
Indeno(1,2,3-cd)pyrene	< 0.0012 µg/L
Sum of PAHs	< 0.004 µg/L
Bisphenol A	< 0.047 µg/L
Bisphenol F	< 0.047 µg/L
Bisphenol S	< 0.047 µg/L
Bisphenol Z	< 0.047 µg/L
Bisphenol AP	< 0.047 µg/L
Diethyl phthalate	0.0085 µg/L
Dimethyl phthalate	0.0067 µg/L
8 other phthalates	< 0.0050 µg/L
Sum of phthalates	0.0152 µg/L (85% reduction)

Free chlorine and fluoride

Free chlorine: 0.24 mg/L at the input, below 0.05 mg/L at the output, which is the quantification limit of the EN ISO 7393-2 method. Fluoride: a dedicated test was run in July 2026 (report 30494) with water spiked at 1 mg/L, analysed by ion chromatography (DIN EN ISO 10304-1) in an ISO/IEC 17025 accredited laboratory. No fluoride was detected at the output: 99.9% reduction, a result verified by a qualified laboratory operator.

Our testing programme continues

• Tested product: the Puure Nano cartridge, our most advanced cartridge (report 25146). Every figure on this page is attributed to it by name.
• A first campaign dosed at ten times the quantification limit. For most substances the output reads "not detected": the demonstrated reduction is then bounded by the precision of the measurement, not by the cartridge. For a few elements dosed too close to that limit, we are re-running the test at one hundred times the limit to measure the actual reduction rather than a floor.
• It takes time. More than 260 parameters, several accredited laboratories, a fresh cartridge for every test: new reports are published here as they are issued, with their number and date, as the July 2026 fluoride test was.
• Minerals are preserved by design. Calcium and magnesium pass through the cartridge at 98 and 99%: Puure filters without demineralising, which reverse osmosis cannot do.