Water treatment regulations and standards are 17 instruments, from EPA drinking-water and discharge rules to NSF/ANSI/CAN 60 certification, AWWA and EN product standards and EU rules, that decide which chemicals a utility or plant may dose, in what quality and up to which limit. Each has its own issuer, edition and compliance date, so which ones apply to a given chemical?
The 17 instruments sit in 6 groups: EPA drinking water, EPA discharge, chemical use and process safety, certification and product standards, EU and international, and building water. Each instrument is mapped to the families of water treatment chemicals it controls.
Every instrument, edition and date here is checked against the issuing body (eCFR, EPA, NSF, AWWA, CEN, EUR-Lex, WHO); see our methodology and fact-checking process.
What Are Water Treatment Regulations and Standards?#
Water treatment regulations are legally binding rules issued by a government, such as the Safe Drinking Water Act rules in 40 CFR 141, while water treatment standards are consensus documents, such as NSF/ANSI/CAN 60 or ANSI/AWWA B300-24, that become binding when a regulation, a state or a purchase specification adopts them. Federal primary standards are enforceable (40 CFR 141); secondary standards are not (40 CFR 143.3).
Which EPA water regulations apply to treatment chemicals?#
EPA water regulations reach treatment chemicals through 4 statutes: the Safe Drinking Water Act, the Clean Water Act, Clean Air Act section 112(r) and FIFRA. Their main instruments are listed below.
- Safe Drinking Water Act (Public Law 93-523, 1974-12-16): MCLs, MRDLs and treatment techniques in 40 CFR 141 for over 148,000 public water systems (EPA, 2026-03-16).
- Clean Water Act: NPDES permits (40 CFR 122), pretreatment (40 CFR 403), effluent guidelines (40 CFR 405 to 471).
- Clean Air Act section 112(r): Risk Management Program, 40 CFR 68.
- FIFRA: registration of slimicides and disinfectants with pesticidal claims (40 CFR 152.15).
A contaminant is regulated once it has an MCL or treatment technique.
How do NSF, AWWA and EN standards differ from regulations?#
NSF/ANSI/CAN 60 sets health-effects requirements for drinking water chemicals, with no performance, taste or odor requirements, and 48 of 50 US states require it in their regulations (NSF, 2019). The 3 standard families cover different questions.
- NSF/ANSI/CAN 60: health effects and a product-specific maximum use level (MUL), the total of all feed points.
- ANSI/AWWA B-series: 49 product-quality standards, B100-25 to B703-24.
- EN standards of CEN/TC 164: purity and impurities, such as EN 878:2016 (aluminium sulfate).
Utilities usually require both NSF/ANSI/CAN 60 certification and the AWWA standard in a chemical bid.
Directory: All 17 Water Treatment Regulations and Standards#
The 17 water treatment regulations and standards below fall into 6 groups: 4 EPA drinking water rules, 3 EPA discharge rules, 3 chemical-use and process-safety rules, 3 certification and product standards, 3 EU and international rules and 1 building water standard. The table compares issuer, type and edition as of 2026-10-20.
| Instrument | Group | Issuer | Jurisdiction | Type | Edition or key date | Controls for treatment chemicals |
|---|---|---|---|---|---|---|
| Safe Drinking Water Act and the treatment rules | 1 | US Congress, EPA | US | statute, 40 CFR 141 to 143 | PL 93-523, 1974-12-16; amended 1986, 1996 | MCLs, MRDLs and treatment techniques that drive coagulant, disinfectant and corrosion-control dosing |
| Lead and Copper Rule (LCR, LCRR, LCRI) | 1 | EPA | US | rule, 40 CFR 141 subpart I | LCRI 2024-10-30; compliance 2027-11-01 | corrosion control: orthophosphate, zinc orthophosphate, silicate, pH and alkalinity adjustment |
| Disinfectants and Disinfection Byproducts Rules | 1 | EPA | US | rule, 40 CFR 141.64, 141.65 | Stage 1 1998-12-16; Stage 2 2006-01-04 | MRDLs for chlorine, chloramines, ClO2; bromate and chlorite MCLs |
| Surface Water Treatment Rules | 1 | EPA | US | rules, 40 CFR 141 subparts H, P, T, W | SWTR 1989-06-29; IESWTR 1998-12-16; LT1 2002-01-14; LT2 2006-01-05 | coagulation and filtration performance (CFE ≤ 0.3 NTU in 95 %), disinfection credits |
| NPDES permits and chemical discharges | 2 | EPA and authorized states | US | permit program, CWA 402, 40 CFR 122 | CWA permit program | additive disclosure, effluent limits and WET for biocides, dechlorinators, inhibitors |
| National Pretreatment Program (40 CFR 403) | 2 | EPA and POTWs | US | rule, CWA 307(b) | 40 CFR 403 (eCFR 2026-10-01) | prohibited discharges (pH below 5.0, flashpoint below 60 °C (140 °F)), local limits |
| Effluent Limitations Guidelines (40 CFR 405-471) | 2 | EPA | US | technology-based limits | 59 point source categories | BPT, BAT, NSPS, PSES, PSNS limits on metals, chlorine and added chemicals |
| FIFRA registration of water treatment biocides | 3 | EPA OPP | US | statute, 40 CFR 152 | 40 CFR 152.15, 152.500 | registration of slimicides, algicides, disinfectants; device rules for on-site generators |
| 21 CFR 173.310 boiler water additives | 3 | FDA | US | regulation | last amended 2023-03-24 (88 FR 17710) | 37 listed additives in (c), 6 in (d) with steam caps |
| EPA RMP and OSHA PSM | 3 | EPA; OSHA | US | rules, 40 CFR 68; 29 CFR 1910.119 | RMP 2024 rule in force; 2026-02-24 proposal not final | threshold quantities for chlorine, ClO2, ammonia, SO2 (ozone under PSM only) |
| NSF/ANSI/CAN 60 | 4 | NSF, ANSI, SCC | US, Canada | health-effects certification standard | first adopted December 1987; 1,150 companies listed (NSF listings, 2026-10-21) | product-specific maximum use levels, annual testing, unannounced inspection |
| AWWA B-series standards | 4 | AWWA (ANSI) | North America | product standards | 49 standards, B100-25 to B703-24 (list 2026-10-20) | purity, impurity limits, testing, packaging and shipping per chemical |
| EN standards for drinking water treatment chemicals | 4 | CEN/TC 164/WG 9 | EU/EEA | product standards | EN 878:2016, EN 17034:2018, EN 888:2023, EN 901:2024 | purity and impurity limits for chemicals for water intended for human consumption |
| EU Drinking Water Directive 2020/2184 | 5 | EU | EU | directive | OJ L 435, 2020-12-23; Article 25 parameters binding 2026-01-12 | Article 12 treatment chemicals and filter media; chlorate, chlorite, HAA5, lead values |
| EU Biocidal Products Regulation | 5 | EU (Commission, ECHA) | EU | Regulation (EU) 528/2012 | 2012-05-22; active chlorine approvals 2019-01-01 to 2028-12-31 | product types PT2, PT5, PT11, PT12 for disinfectants, cooling biocides and slimicides |
| WHO Guidelines for Drinking-water Quality | 5 | WHO | international | guidelines | 4th edition incl. 1st to 3rd addenda, 2026-06-17 | guideline values for disinfectants and byproducts; reference for national rules |
| ASHRAE 188 and Legionella water management programs | 6 | ASHRAE (ANSI) | US (building codes) | consensus standard | ANSI/ASHRAE 188-2021; Guideline 12-2023 | water management programs that set biocide and residual control in building water |
1. EPA drinking water rules (4)#
EPA drinking water rules are the primary drinking water regulations under the Safe Drinking Water Act, in 4 instruments: the Act, the Lead and Copper Rule, the DBP Rules and the Surface Water Treatment Rules. The LCRI (2024-10-30) lowers the lead action level to 0.010 mg/L from 2027-11-01.
2. EPA discharge rules under the Clean Water Act (3)#
EPA discharge rules control what a plant releases, in 3 instruments: NPDES permits for direct discharges, the National Pretreatment Program for sewer discharges and Effluent Limitations Guidelines for 59 industrial categories. NPDES applications disclose chemical additives, which effluent limits and whole effluent toxicity tests then control.
3. Chemical-use and process-safety rules: EPA, FDA and OSHA (3)#
Chemical-use and process-safety rules govern what a chemical is, not what it removes, in 3 instruments: FIFRA for biocides, 21 CFR 173.310 for boiler additives in food-contact steam and EPA RMP with OSHA PSM for stored toxic gases. Section 173.310 lists 37 substances in paragraph (c) and 6 in (d).
4. Certification and product standards: NSF, AWWA and EN (3)#
Certification and product standards define the health safety and quality of a treatment chemical, in 3 instruments: NSF/ANSI/CAN 60, the AWWA B-series and the EN standards of CEN/TC 164. NSF/ANSI/CAN 60 lists 1,150 companies (NSF listings, 2026-10-21). EN 17034:2018 superseded the withdrawn EN 881:2004 and EN 883:2004.
5. EU and international rules (3)#
EU and international rules set drinking water and biocide requirements outside the United States, in 3 instruments: the EU Drinking Water Directive 2020/2184, the EU Biocidal Products Regulation 528/2012 and the WHO Guidelines for Drinking-water Quality. Article 12 of the Directive covers treatment chemicals; BPR product types include PT5 drinking water and PT11 cooling systems.
6. Building water management: ASHRAE 188 (1)#
Building water management standards set how an owner controls Legionella risk, in 1 instrument: ANSI/ASHRAE Standard 188-2021, used with ASHRAE Guideline 12-2023. It requires a building survey, a water management program, preventive measures and documentation.
Which Rules Apply to Which Water Treatment Chemical?#
The rules that apply to a water treatment chemical depend on 4 facts: the water it treats, where that water goes, what the chemical claims and how much is stored on site. The 4 checks run in order.
- Check the water: drinking water brings in NSF/ANSI/CAN 60, the AWWA or EN standard and 40 CFR 141 limits.
- Trace the discharge: a river needs an NPDES permit, a sewer means 40 CFR 403 and local limits.
- Read the label claim: a slimicide or disinfectant claim makes a product a pesticide under FIFRA (40 CFR 152.15).
- Count the stored quantity: chlorine above 1,500 lb (680 kg) triggers OSHA PSM, above 2,500 lb (1,134 kg) EPA RMP.
Worked example: one 1-ton chlorine cylinder holds 2,000 lb (907 kg), above the PSM threshold and below the RMP threshold. The matrix compares 8 chemicals across 5 rule types.
| Chemical | Certification and product standard | Drinking water limit (US) | Discharge or use rule | RMP / PSM threshold | EU |
|---|---|---|---|---|---|
| Chlorine (gas) | NSF/ANSI/CAN 60; ANSI/AWWA B301-24; EN 937:2016 | MRDL 4.0 mg/L as Cl2 (40 CFR 141.65) | NPDES chlorine limits; steam electric cooling tower blowdown FAC 0.2 mg/L average, 0.5 mg/L maximum (40 CFR 423.13) | 2,500 lb (1,134 kg) / 1,500 lb (680 kg) | BPR PT2 and PT5, Reg. (EU) 2017/1275 |
| Sodium hypochlorite | NSF/ANSI/CAN 60; ANSI/AWWA B300-24; EN 901:2024 | MRDL 4.0 mg/L as Cl2 | FIFRA registration when sold with pesticidal claims | not RMP-listed | BPR PT1 to PT5, Reg. (EU) 2017/1273 |
| Chlorine dioxide (from sodium chlorite) | NSF/ANSI/CAN 60; ANSI/AWWA B303-24 (sodium chlorite); EN 12671:2016 (in situ), EN 938:2016 (sodium chlorite) | MRDL 0.8 mg/L as ClO2; chlorite MCL 1.0 mg/L | see the NPDES page | 1,000 lb (454 kg) / 1,000 lb (454 kg) | chlorate and chlorite 0.25 mg/L, 0.70 mg/L where ClO2 is used (DWD) |
| Aluminum sulfate and polyaluminum chloride | NSF/ANSI/CAN 60 (listing condition: aluminum in finished water ≤ 2 mg/L); ANSI/AWWA B403-24 and B408-25; EN 878:2016 and EN 17034:2018 | SMCL aluminum 0.05 to 0.2 mg/L (non-enforceable) | residuals under NPDES | not listed | aluminum indicator 200 µg/L (DWD) |
| Polyacrylamide flocculant | NSF/ANSI/CAN 60; ANSI/AWWA B453-24; EN 1407 and EN 1410 | treatment technique: 0.05 % acrylamide monomer dosed at 1 ppm (40 CFR 141.111) | n/a | not listed | acrylamide 0.10 µg/L (DWD) |
| Orthophosphate and zinc orthophosphate | NSF/ANSI/CAN 60; ANSI/AWWA B506-25 (zinc orthophosphate), B507-23 (phosphoric acid) | lead action level 0.010 mg/L from 2027-11-01 (LCRI) | phosphorus limits in NPDES permits | not listed | lead 10 µg/L until 2036-01-12, then 5 µg/L (DWD) |
| Fluorosilicic acid | NSF/ANSI/CAN 60; ANSI/AWWA B703-24; EN 12175:2022 | fluoride MCL 4.0 mg/L, SMCL 2.0 mg/L (0.7 mg/L is the US PHS optimal level, not a limit) | n/a | not RMP-listed | fluoride 1.5 mg/L (DWD) |
| Boiler neutralizing amines (cyclohexylamine, morpholine, DEAE) | not drinking water chemicals | n/a | 21 CFR 173.310(d): cyclohexylamine 10 ppm, morpholine 10 ppm, DEAE 15 ppm in steam (not for steam contacting milk and milk products) | not listed here | n/a |
Each chemical's NSF status, CAS number and function is filterable in the water treatment chemical database.
Key Limits in Water Treatment Regulations at a Glance#
The limits a chemical program meets most often are the residual disinfectant levels of 4.0 mg/L as Cl2 for chlorine and chloramines and 0.8 mg/L as ClO2 (40 CFR 141.65), TTHM 0.080 mg/L and HAA5 0.060 mg/L, and the lead action level. The table lists 12 limits in force on 2026-10-20.
| Limit | Value (unit, basis) | Instrument and section | Date | Status |
|---|---|---|---|---|
| MRDL chlorine; chloramines | 4.0 mg/L as Cl2 each (running annual average) | 40 CFR 141.65, Stage 1 DBPR | 1998-12-16 | in force |
| MRDL chlorine dioxide | 0.8 mg/L as ClO2 | 40 CFR 141.65 | 1998-12-16 | in force |
| TTHM; HAA5 | 0.080 mg/L; 0.060 mg/L (LRAA) | 40 CFR 141.64, Stage 2 DBPR | 2006-01-04 | in force |
| Bromate; chlorite | 0.010 mg/L; 1.0 mg/L | 40 CFR 141.64 | 1998-12-16 | in force |
| Lead action level (90th percentile); copper | lead 0.015 mg/L until 2027-10-31, 0.010 mg/L from 2027-11-01; copper 1.3 mg/L | 40 CFR 141.80(c), LCRI | 2024-10-30 | in force, compliance 2027-11-01 |
| PFOA; PFOS | 4.0 ng/L each | 40 CFR 141.61(c), 89 FR 32532 | 2024-04-26 | codified; MCL compliance 2029-04-26; 2026-05-18 proposals pending |
| Acrylamide; epichlorohydrin | treatment technique: 0.05 % monomer at 1 ppm; 0.01 % at 20 ppm; annual certification to the State | 40 CFR 141.111 | 1991-01-30 | in force |
| Combined filter effluent turbidity | ≤ 0.3 NTU in ≥ 95 % of monthly measurements, never > 1 NTU | 40 CFR 141.173, IESWTR | 1998-12-16 | in force |
| Sewer discharge pH (federal) | no discharge below pH 5.0 unless the POTW is designed for it | 40 CFR 403.5(b)(2) | eCFR 2026-10-01 | in force |
| RMP; PSM threshold, chlorine | 2,500 lb (1,134 kg); 1,500 lb (680 kg) | 40 CFR 68.130; 29 CFR 1910.119 App. A | eCFR 2026-10-01 | in force |
| Food-contact steam amines | cyclohexylamine 10 ppm, DEAE 15 ppm, morpholine 10 ppm, octadecylamine 3 ppm in steam; hydrazine zero | 21 CFR 173.310(d) | last amended 2023-03-24 | in force |
| EU chlorate; chlorite | 0.25 mg/L each; 0.70 mg/L where ClO2 or another chlorate-generating method is used | Directive (EU) 2020/2184, Annex I Part B | binding 2026-01-12 | in force (EU) |
Which Water Treatment Regulations Change Next? Final, Pending and Proposed Dates#
The next binding change for treatment chemicals in US drinking water is the Lead and Copper Rule Improvements compliance date of 2027-11-01, when the lead action level falls from 0.015 to 0.010 mg/L (89 FR 86418, 2024-10-30).
EPA's 2 PFAS proposals of 2026-05-18 are pending, so the PFAS MCLs stay codified with compliance on 2029-04-26. The RMP proposal of 2026-02-24 closed for comment on 2026-05-11 and is not final. The timeline lists 11 dated changes to 2036.
| Date | Jurisdiction | Instrument | Change for treatment chemicals | Status |
|---|---|---|---|---|
| 2024-03-11 | US | EPA RMP "Safer Communities by Chemical Accident Prevention" (89 FR 17622) | RMP revisions | final, in force |
| 2024-04-26 | US | PFAS NPDWR (89 FR 32532) | PFOA, PFOS 4.0 ng/L; PFHxS, PFNA, HFPO-DA 10 ng/L; Hazard Index 1 | final, codified |
| 2024-10-30 | US | LCRI (89 FR 86418) | lead action level 0.010 mg/L; lead service lines replaced within 10 years | final |
| 2026-01-12 | EU | DWD Article 25 | chlorate, chlorite, HAA5 and PFAS parameters binding | in force |
| 2026-02-24 | US | EPA RMP "Common Sense Approach to Chemical Accident Prevention" | proposed revisions; comments closed 2026-05-11 | proposed, not final |
| 2026-05-18 | US | EPA PFAS proposals (2) | option to 2031 for PFOA and PFOS; rescission of PFHxS, PFNA, HFPO-DA and Hazard Index limits | proposed, pending |
| 2026-06-17 | WHO | GDWQ 4th edition incl. 1st to 3rd addenda | consolidated edition | published |
| 2027-11-01 | US | LCRI compliance | lead action level 0.010 mg/L applies; corrosion control programs re-evaluated | compliance date |
| 2028-12-31 | EU | BPR active chlorine approvals (2017/1273, 1274, 1275) | approvals expire as adopted; renewal decision needed | pending expiry |
| 2029-04-26 | US | PFAS MCL compliance (as codified) | GAC, ion exchange or RO in place | compliance date (2031 for PFOA and PFOS only if the proposal is finalized) |
| 2036-01-12 | EU | DWD Annex I | lead 5 µg/L, chromium 25 µg/L | pending |
Dated rule changes, NSF/ANSI/CAN 60 revisions and AWWA editions are tracked as water treatment chemicals news on regulations.
Who Helps With Water Treatment Regulations and Compliance?#
Compliance with water treatment regulations is shared by the plant, its program provider, which runs monitoring and reports, and its chemical supplier, which documents NSF/ANSI/CAN 60 listing and the AWWA or EN specification.
NSF certification ends when a product is repackaged, diluted or blended at an uncertified site. How to compare program providers is explained under water treatment companies.
This page summarizes official requirements for information only and is not legal advice; for a compliance decision, check the current official text and consult the competent authority or a qualified legal adviser.
How Do EPA Regulations Compare With State, EU and WHO Rules?#
EPA regulations set the federal floor, states with primacy (40 CFR 142) enforce them and may adopt stricter rules, and EU and WHO instruments apply outside the United States.
What is the difference between an MCL, an MCLG, a treatment technique and an MRDL?#
An MCLG is the health goal, an MCL the enforceable limit set as close to it as feasible, a treatment technique replaces an MCL where a level cannot be measured feasibly, and an MRDL caps a disinfectant residual. Acrylamide is a treatment technique (40 CFR 141.111).
What are EPA secondary drinking water standards?#
EPA secondary drinking water standards are non-enforceable levels for taste, color and appearance in 40 CFR 143.3, such as aluminum 0.05 to 0.2 mg/L, iron 0.3 mg/L and pH 6.5 to 8.5.
The chemicals that keep finished water inside them are covered under drinking water treatment chemicals.
What is the MCL for arsenic?#
The arsenic MCL is 0.010 mg/L (10 µg/L) under 40 CFR 141.62, with coagulation and filtration, activated alumina and ion exchange among the best available technologies.
What wastewater guidelines does the EPA set under the Clean Water Act?#
Under the Clean Water Act the EPA sets effluent guidelines for 59 industrial categories (40 CFR 405 to 471), pretreatment prohibitions for sewer dischargers (40 CFR 403.5) and the NPDES permit framework (40 CFR 122).
The chemistry each industry uses to meet them is compared under industrial wastewater treatment chemicals.
Do WHO guidelines and EU rules apply in the United States?#
No: WHO guideline values are references for national standards, and the EU Drinking Water Directive 2020/2184 binds EU member states only, so US systems follow 40 CFR 141 and state rules.
Is NSF/ANSI/CAN 60 certification required by federal law?#
No federal rule requires NSF/ANSI/CAN 60 certification: 48 of 50 states require it in their regulations, and 9 of 13 Canadian provinces and territories do (NSF, 2019).
Do state drinking water rules differ from EPA rules?#
State rules can be stricter than EPA rules but not weaker, and many states add design standards such as the Recommended Standards for Water Works (2022 edition) of the Ten States board.