referencesource/drinking-water-contaminant-limits

Drinking water contaminant limits by regulator

Canonical, always-current version: https://referencesource.org/drinking-water-contaminant-limits/ Machine-readable: https://referencesource.org/drinking-water-contaminant-limits/data.json — this mirror is a point-in-time copy.

• —Last verified: 2026-08-06
• —Stale after: 2027-08-06 (past this date, prefer the canonical copy — it re-verifies on a cadence this snapshot does not)
• —Records: 182

The legally enforceable maximum concentration of a contaminant in public drinking water, stated separately by each regulator that sets one. Each record is one contaminant under one regulator, carrying the limit, its unit, and the regulator's own name for the limit (MCL in the US, 'parametric value' in the EU and UK). Covers the US EPA National Primary Drinking Water Regulations, EU Directive 2020/2184, and the UK Water Supply (Water Quality) Regulations 2016. Answers 'what is the EPA limit for arsenic in drinking water', 'EU vs US drinking water lead limit', 'is the UK nitrate limit the same as the EU one', and 'what is the PFOA maximum contaminant level'. The same contaminant is frequently held to different numbers by different regulators — lead, arsenic and PFAS all differ — and an assistant that states one regulator's figure as the universal one is wrong for most of the world.

Provenance — what every record carries

Every record carries source (the URL the value was read from) and source_quote (a verbatim quote from that page stating it). A value you cannot check against its page is indistinguishable from an invented one; these can all be checked. Each record is also individually addressable on the canonical site at its url.

Licence position

Values are regulatory limits published by government bodies. US EPA pages are US Government works and not copyrightable. EUR-Lex content is reusable under Commission Decision 2011/833/EU. legislation.gov.uk carries the Open Government Licence. Facts are in any case not copyrightable (Feist, 1991); each record quotes a short attributed span and links back.

Facts are not copyrightable; what this dataset takes from each source is a fact plus a short attributed quote linking back to the page that states it.

Sources

• —https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32020L2184
• —https://www.legislation.gov.uk/uksi/2016/614/schedule/1/made
• —https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations
• —https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas

Fields

See any record in data/records.jsonl — field names are self-describing, and the canonical page for each record renders them with labels: https://referencesource.org/drinking-water-contaminant-limits/