Every value on WaterTreatmentChemicals.net, from an NSF/ANSI/CAN 60 maximum use level to an AWWA edition or an EPA limit, is checked against one of 10 named primary sources and published with its source and date. Which sources, which one wins, and how current is each number?
Each value passes 6 fact-check steps, carries its dose basis and dated edition, and is re-checked monthly for the eCFR and the Federal Register. Confirmed errors are corrected on every page, and no company pays for a mention. The same method covers every page about water treatment chemicals, from coagulants to ion-exchange resins.
Which 10 Primary Sources Supply the Values?#
The 10 primary sources are the NSF listings, AWWA, CEN, EPA, eCFR, the Federal Register, EUR-Lex, ECHA, WHO and PubChem, each used for the type of value it issues or registers. Table 1 shows what each source supplies and how its values are dated.
| # | Source | What it supplies on this site | How it is dated in copy | Covered on this site |
|---|---|---|---|---|
| 1 | NSF listings (NSF/ANSI/CAN 60 drinking water treatment chemicals) | certification status, maximum use level (mg/L as product), listing conditions such as aluminum not to exceed 2 mg/L | "NSF listings, 2026-10-21" | NSF/ANSI/CAN 60 |
| 2 | AWWA (American Water Works Association) standards list | ANSI/AWWA B-series product standards for chemicals and media | full edition, such as "ANSI/AWWA B403-24" | AWWA B-series standards |
| 3 | CEN (European Committee for Standardization), TC 164 WG 9 catalogue | EN standards for chemicals used to treat water intended for human consumption | full edition, such as "EN 878:2016" | EN standards for drinking water treatment chemicals |
| 4 | EPA (US Environmental Protection Agency) | guidance, rule pages, Water Treatment Chemical Supply Chain Profiles | page or document date, such as "EPA, updated 2026-06-30" | Safe Drinking Water Act |
| 5 | eCFR (Electronic Code of Federal Regulations) | current codified US limits, such as 40 CFR 141, 40 CFR 143 and 21 CFR 173.310 | "as of 2026-10-01" with the section | cited in the text of each rule page |
| 6 | Federal Register | rule history: publication, effective and compliance dates | volume, page and date, such as "89 FR 86418, 2024-10-30" | cited in the text of each rule page |
| 7 | EUR-Lex | EU directives and regulations, such as Directive (EU) 2020/2184 and Regulation (EU) 528/2012 | instrument number, article and date | EU Drinking Water Directive 2020/2184 |
| 8 | ECHA (European Chemicals Agency) | CLP classification and notified hazard data | label "harmonised (CLP Annex VI)" or "notified (ECHA C&L)" | hazard section of each chemical page |
| 9 | WHO (World Health Organization) | Guidelines for Drinking-water Quality guideline values | "fourth edition incorporating the first, second and third addenda, 17 June 2026" | WHO Guidelines for Drinking-water Quality |
| 10 | PubChem (US National Library of Medicine) | chemical identity: CAS number, formula, molecular weight | date the identity was checked | every chemical with function, CAS and NSF/ANSI 60 status |
Further sources, such as Health Canada, Australia's NHMRC guidelines and PubMed-indexed journals, are named in the sentence that uses them.
Standards and certification: NSF listings, AWWA and CEN#
Certification status and maximum use levels come from the NSF/ANSI/CAN 60 listings, cited with the listing date; product-quality requirements come from the AWWA standards list and the CEN/TC 164 catalogue, cited with the full edition, such as ANSI/AWWA B403-24 or EN 878:2016. A maximum use level is product-specific, stated as product, totaled across all application points.
US regulations: EPA, eCFR and the Federal Register#
US limits are read from the eCFR text in force on a stated date, here 2026-10-01, and their history and compliance dates from the Federal Register, so a value reads like "0.010 mg/L, 40 CFR 141.80(c), 89 FR 86418, 2024-10-30". EPA supplies guidance and the Water Treatment Chemical Supply Chain Profiles, dated by page update.
The full list of water treatment regulations and standards is indexed by issuer.
EU rules and hazard data: EUR-Lex and ECHA#
EU values come from the official texts on EUR-Lex, such as Directive (EU) 2020/2184 for drinking water and Regulation (EU) 528/2012 for biocides, and every hazard statement is labelled "harmonised (CLP Annex VI)" or "notified (ECHA C&L)". Treatment chemicals fall under Article 12 of the directive, materials in contact with water under Article 11. Biocide approvals come from the EU Biocidal Products Regulation.
Global guidance and chemical identity: WHO and PubChem#
International guideline values come from the WHO Guidelines for Drinking-water Quality, fourth edition incorporating the first, second and third addenda (17 June 2026), and chemical identity (CAS number, formula, molecular weight) from PubChem. Look-alikes are checked: aluminum sulfate is CAS 10043-01-3, while 10043-67-1 is potassium alum.
How Are Sources Ranked When They Disagree?#
The official text wins: legal instruments, official registers and standards catalogues outrank guidance, guidance outranks studies, and supplier documents come last. The 5 source tiers, from strongest to weakest, are listed below.
- Legal texts and official registers: eCFR, Federal Register, EUR-Lex, NSF listings, ECHA, PubChem for identity.
- Standards catalogues: AWWA, CEN/TC 164, ASHRAE.
- Government and intergovernmental guidance: EPA, WHO, Health Canada, NHMRC.
- Peer-reviewed studies: cited by researcher, institution and year, written as results, never as limits.
- Handbooks and supplier documents: named as the source of a figure, labelled "supplier figure".
A newer official text replaces an older value on every page; conflicting values that no higher source settles are left out.
How Is Each Value Fact-Checked? 6 Steps#
Each value is fact-checked in 6 steps, from finding the primary source to matching the same value on every page that states it. The 6 fact-check steps are listed below in the order they run.
- Find the primary source that issues the value, not a page that repeats it.
- Match number, unit and basis: as product, as active, as CaCO3, as Cl2.
- Confirm jurisdiction and status: US, EU or WHO; proposed, final, effective or in compliance.
- Record the source, its section or edition, and the date checked.
- Align the value on every page that states it.
- Withhold any value that cannot be confirmed.
A coagulant overview, a chemical page and a standards page therefore state the same limit in the same words. How is each value then written?
How Is Every Value Written? Units, Dose Basis, Editions and Dates#
Every value is written metric first with US customary units in parallel, with its dose basis, and with the edition or date of its source, such as "5 to 100 mg/L (ppm) as product" or "NSF listings, 2026-10-21". Unit pairs run mg/L (ppm), °C (°F), bar (psig), m³/h (gpm) and kg/d (lb/day). Conversions are fixed site-wide: ppm equals mg/L only at a density of about 1. Table 2 shows the rule per value type.
| Value type | Rule | Example as written on the site |
|---|---|---|
| Dose | metric and US units, dose basis always stated | "5 to 100 mg/L (ppm) as product" |
| Feed rate | one formula site-wide | "lb/day = mg/L x MGD x 8.34 / purity" |
| Hardness and alkalinity | expressed as CaCO3; fixed conversion | "1 gpg = 17.1 mg/L as CaCO3" |
| Phosphate | ion basis stated; fixed conversion | "mg/L as PO4 x 0.326 = mg/L as P" |
| NSF maximum use level | product-specific, as product, total across all feed points, dated; range and most common value, never one class value | "most common 250 mg/L as product (NSF listings, 2026-10-21)" |
| Standard | full edition; an edition that cannot be confirmed is written without a year | "ANSI/AWWA B403-24"; "EN 878:2016" |
| Regulatory value | instrument, section, date; jurisdiction named | "lead action level 0.010 mg/L, 40 CFR 141.80(c)" under the Lead and Copper Rule |
| Pending rule | proposal, final, effective and compliance dates kept apart | "EPA proposals of 2026-05-18 (pending)" |
| Hazard statement | harmonised versus notified label | "sodium hypochlorite: H314, H318, H400, H410 harmonised (CLP Annex VI); H290 notified (ECHA C&L)" |
| Identity | CAS from PubChem; salt and hydrate numbers stated as "primary; also X" | "aluminum sulfate CAS 10043-01-3" |
| Market size | analyst estimate with publisher and year | "Grand View Research, 2025" |
| Supplier figure | labelled as such; never a recommendation | "supplier figure" |
Feed rates follow one formula, lb/day = dose (mg/L) x flow (MGD) x 8.34 / purity, which the chemical dosage and feed rate calculator applies in metric and US units.
Pending versus final rules#
A pending rule is never written as law: proposal, final, effective and compliance dates are kept apart. The PFAS drinking water rule (89 FR 32532, 2024-04-26) is still codified on 2026-10-01, while EPA's 2026-05-18 proposals to change it are pending. The lead action level of 0.010 mg/L under the Lead and Copper Rule Improvements applies from 2027-11-01; 0.015 mg/L applies until then.
Market figures and company data#
Market sizes are analyst estimates and are always written with the publisher and year, such as "Grand View Research, 2025", while company figures come from the company's annual report or SEC Form 10-K filing. Estimates for the water treatment chemicals market are never written as fact, and acquisition dates are completion dates.
How Often Are Values Re-Checked?#
Values are re-checked on a fixed cycle per source: NSF listings every quarter and before a chemical page publishes, the Federal Register and eCFR every month, and the AWWA standards list every quarter. Table 3 lists the cycle per source.
| Source | Re-checked | Why it changes |
|---|---|---|
| NSF listings | every quarter and before a chemical page publishes | listings change continuously (products, maximum use levels, manufacturers) |
| Federal Register and eCFR | every month | proposals, final rules, effective and compliance dates |
| AWWA standards list | every quarter | B-standards are revised on a roughly five-year cycle |
| CEN catalogue, EUR-Lex (EU drinking water and biocide rules), WHO addenda, 21 CFR 173.310, ASHRAE, OSHA and NIOSH limits | on each published change | new editions, approvals, renewals, amendments |
| Market estimates | yearly | publishers revise their estimates each year |
How Are Errors Reported and Corrected?#
Readers report an error through the contact page, the value is checked again against its primary source, and a confirmed error is corrected on every page that states it. The primary source decides, not the report.
What counts as a correction and how it is shown are set out in the editorial policy on corrections.
Is the Methodology Independent of Suppliers and Lead Partners?#
Yes: no company pays for a value, a ranking or a mention, the site sells no chemical, and no lead partner has been chosen; quote requests go to independent providers and suppliers. Who runs the site and why it stays vendor-neutral is explained on about WaterTreatmentChemicals.net, an independent water treatment chemicals reference.
Companies are not ranked, and trust pages carry no ads.
How leads are passed on and how any future sponsored listing would be marked is set out in the editorial policy on independence and lead partners.
What Does the Methodology Not Cover?#
The methodology covers chemicals and media dosed or specified in industrial, municipal and utility water systems; pool, spa, pond, aquarium, household, emergency, medical, food, cosmetic and agricultural uses are never answered. Within that scope, 5 questions come up once a reader relies on a value.
Does WaterTreatmentChemicals.net test or certify chemicals?#
Certification under NSF/ANSI/CAN 60 is issued by accredited certification bodies, and a product's status is shown only by its own listing, cited with the listing date. How listings and maximum use levels work is explained under NSF/ANSI/CAN 60 certification.
Are the values legal or engineering advice?#
No: the values are a dated reference, and a utility or plant should confirm the official text, its permit and the product documents before acting. Food-plant steam chemicals carry only "not listed in 21 CFR 173.310", never an eligibility claim.
Why can a value differ from a supplier data sheet?#
A supplier sheet often uses a different basis or a single product: NSF maximum use levels are product-specific, and hypochlorite sold as 12.5 trade % holds 125 g/L available chlorine. Certification also lapses when a product is repackaged, diluted or blended at an uncertified site.
How are new regulations tracked between page updates?#
New and pending regulations are followed in the Federal Register, EUR-Lex and the NSF and AWWA lists. Each change is reported in water treatment chemicals news with links to the pages it changes.
How do I contact WaterTreatmentChemicals.net about an error?#
Send the page address, the value and, where possible, the primary source you checked; the value is re-checked against that source. Use the form on contact WaterTreatmentChemicals.net.