How limits are set
TWO CATEGORY RULES govern every row. (1) THE MATERIAL-FAMILY RULE: a row's published ceiling is anchored only where a sovereign instrument governs element migration into food from that row's PRINCIPAL food-contact material family.
Polymer surfaces anchor EU 10/2011 Annex II directly, or by disclosed read-across where the instrument expressly excludes the polymer (silicone under Art. 2(2)(c), ion-exchange resin under Art. 2(2)(a)) or does not reach it (cured liquid-applied coatings, paper and board, wood). Metal, alloy, ceramic-glaze, vitreous-enamel and glass surfaces have no sovereign migration ceiling in the register, so those rows are controls with mandatory testing and no invented number.
(2) THE COMPONENT RULE: every food-contact COMPONENT of an article is held to the regime of its own material family, and where a component's family has no sovereign ceiling that component is under control. A row's published cells state the ceiling for its principal food-contact material; the component plan names the other components, the regime each falls under, and which component is expected to bind.
A result from a non-binding component does not represent the article: a can body wall does not represent its seam, a vacuum bottle wall does not represent its base-plug solder, a plain tumbler does not represent a decorated one, a blender jar does not represent its blade assembly, and a cold reservoir does not represent a post-descaling draw.
Master Limit Table
All values in ppb (µg/kg), as-sold basis. 9 of 11 analytes carry a firm ceiling; the remaining 2 are toxic species bounded by their parent totals (species ≤ total, measured on every lot), so every analyte carries an enforceable ceiling. A brand meeting every value on a like-for-like basis qualifies for the mark.
| Analyte | HMTc limit | Binding basis |
|---|---|---|
| Lead (Pb) | 5 | government read-across (EU) |
| Inorganic arsenic (iAs) | bounded | ≤ total tAs, measured every lot (see note) |
| Total arsenic (tAs) | 10 | government read-across (EU) |
| Mercury, total (tHg) | 1 | government read-across (EU) |
| Methylmercury (MeHg) | bounded | ≤ total tHg, measured every lot (see note) |
| Cadmium (Cd) | 2 | government read-across (AU) |
| Hexavalent chromium (Cr-VI) | 10 | government read-across (US-CA) |
| Nickel (Ni) | 20 | government read-across (EU) |
| Tin (Sn) | 100000 | government read-across (EU) |
| Aluminium (Al) | 200 | government read-across (EU) |
| Total chromium (Cr) | 50 | government read-across (AU) |
Every claim analyte is equal at the gate. A product is certified only when every analyte is at or below 100% of its published government floor or disclosed read-across; above the limit, on any metal, it is not certified and carries no mark.
Derivation
The full derivation for Water filters. Each row lists every government maximum level in force worldwide, converted to the as-sold basis; the HMTc limit is the strictest of them, and the last column names which sovereign law binds. A blank cell means that government sets no limit for this analyte in this product.
| Analyte | HMTc | Binds |
|---|---|---|
| Lead (Pb) | 5² | read-across |
| Inorganic arsenic (iAs) | bounded&sup5; | species ≤ tAs |
| Total arsenic (tAs) | 10² | read-across |
| Mercury, total (tHg) | 1² | read-across |
| Methylmercury (MeHg) | bounded&sup5; | species ≤ tHg |
| Cadmium (Cd) | 2² | read-across |
| Hexavalent chromium (Cr-VI) | 10² | read-across |
| Nickel (Ni) | 20² | read-across |
| Tin (Sn) | 100000² | read-across |
| Aluminium (Al) | 200² | read-across |
| Total chromium (Cr) | 50² | read-across |
All values µg/kg (ppb), as-sold basis. ² no government regulates this analyte for this exact product form: the value is a disclosed read-across from the nearest applicable government maximum, and the derivation names the instrument it comes from. It is never taken from occurrence data. After publication the standards ratchet may tighten it, using certified-lot results only. ³ not material in this matrix: measured but with no standalone number, controlled by packaging control or by the total-metal screen, not an invented value. &sup5; a toxic species governed by and bounded by its parent total (for example inorganic arsenic ≤ total arsenic): the species can never exceed the total, so the total ceiling is the species ceiling. The total metal is measured on every lot and the species is established at baseline; no separate species ceiling is published. On ongoing lots the species is speciated whenever the total exceeds its limit.
Occurrence and derivation rationale
For each analyte on the panel: what the peer-reviewed and survey literature measured in this category, cited one way to the Heavy Metal Index, and the Method v2.0 reasoning behind the certification limit — including, where no government sets a number, why the program sets one anyway. Occurrence figures are literature findings; the derivation is the certifier's.
1 study in the corpus measured lead in Water filters (146 samples reported across those studies): Decharat 2020.
HMTc sets 5 ppb by read-across: Pb 5 ug/kg: disclosed read-across from EU eu20202184_pb_drinking_water_5 (water intended for human consumption). Filled by the completeness sweep; nearest applicable sovereign for this matrix and basis. Why lead is limited →
The corpus holds 1 measurement of inorganic arsenic in Water filters (622 samples reported across those studies), which the determination below is tested against: Abuawad 2023.
HMTc sets no standalone inorganic arsenic limit for Water filters. iAs is a component of tAs and bounded by it (iAs <= tAs), so the tAs ceiling is the iAs ceiling; no separate iAs number is published. tAs is measured on every lot, and iAs is speciated only when tAs exceeds its limit. The analyte is controlled by iAs speciation reflexed when the parent total reaches min(species limit, 50 percent of the parent-total limit); the species never substitutes for the parent-total report, not a standalone number. Why inorganic arsenic is limited →
1 study in the corpus measured total arsenic in Water filters (622 samples reported across those studies): Abuawad 2023.
HMTc sets 10 ppb by read-across: tAs 10 ug/kg: disclosed read-across from EU eu20202184_tas_drinking_water_10 (water intended for human consumption). Filled by the completeness sweep; nearest applicable sovereign for this matrix and basis. Why total arsenic is limited →
1 study in the corpus measured cadmium in Water filters (146 samples reported across those studies): Decharat 2020.
HMTc sets 2 ppb by read-across: Cd 2 ug/kg: disclosed read-across from AU nhmrc2025_cd_drinking_water_2 (drinking water). Filled by the completeness sweep; nearest applicable sovereign for this matrix and basis. Why cadmium is limited →
Risk Flag
On the published occurrence literature to date, Water filters shows no systematic gap between typical market levels and the limit — the limit being the strictest government maximum for the product (Method v2.0). Certification is decided on a product’s own tested result, not on a distribution; an individual lot or supplier can still exceed a limit.
See the cross-category summary of the ingredients that most often struggle.
Cite this standard
Pendergrass, K. (2026). Water filters: HMTc standard (Standard No. 10.83138/hmtc.std.23.water-filters). Institute of Contaminant Standards. https://doi.org/10.83138/hmtc.std.23.water-filters
© 2026 Institute of Contaminant Standards / Heavy Metal Certified. All rights reserved.
The literature baseline for every analyte is maintained independently at the Heavy Metal Index. This certification standard applies those findings; the two are kept editorially separate by design.