The Independent Reference for Water Treatment Chemicals
WaterTreatmentChemicals.net is an independent reference for water treatment chemicals: 16 chemical families, 7 application programs and the EPA, NSF/ANSI/CAN 60, AWWA and EU rules that govern them, with every dose stated with its basis in metric and US units.
Chemical families
7 of 16 family guides published. Families without a link are in preparation.
- Coagulants
- Flocculants
- Scale Inhibitors
- Phosphates
- Corrosion Inhibitors
- Oxygen Scavengers
- Neutralizing Amines
- Biocides
- Oxidants and Oxidizing Biocides
- pH Adjustment Chemicals
- Dechlorination Chemicals
- Chelating Agents
- Defoamers and Antifoams
- Descaling and Chemical Cleaning Agents
- Ion Exchange Resins
- Adsorbents and Filter Media
Programs by application
5 of 7 application guides published.
- Cooling Tower Water Treatment
- Boiler Water Treatment
- Reverse Osmosis and Membrane Chemicals
- Wastewater Treatment Chemicals
- Drinking Water Treatment Chemicals
- Closed Loop Water Treatment
- Produced Water Treatment Chemicals
Which chemical, at which dose, under which rule, for which system?
The 16 families run from coagulants, flocculants and scale inhibitors to ion exchange resins and filter media; the 7 systems run from cooling towers and boilers to closed loops and produced water. Every family, its classes and the complete chemical list start on the overview of water treatment chemicals.
A chemical database, 15 dated key values such as the 4.0 mg/L (ppm) as Cl2 chlorine MRDL, 7 chemistry concepts with calculators, 4 layers of rules and 2 buying routes complete the reference, which sells no chemical.
Every value on this site is checked against primary sources (eCFR, Federal Register, NSF listings, AWWA, CEN, EPA, WHO, EUR-Lex); see our methodology and fact-checking process.
What Is WaterTreatmentChemicals.net?#
WaterTreatmentChemicals.net is a vendor-neutral technical reference that explains what each water treatment chemical is, how it works, where and at what dose it is used, how it is controlled and which rules apply, and it sells no chemical. It covers chemicals and media that operators, engineers and utilities dose or specify in industrial, municipal and utility systems, and no consumer uses.
The reference has 6 parts, listed below in navigation order.
- Chemical families: 16 hubs from coagulants to filter media
- Chemical database: CAS number, function and NSF/ANSI/CAN 60 status per chemical
- Applications: chemical programs for 7 systems
- Chemistry concepts and calculators: coagulation, scaling indices, cycles, chlorination
- Regulations and standards: EPA, NSF, AWWA, CEN and EU rules
- Providers and suppliers: how programs and chemicals are bought
The reference is written for 4 groups: plant operators, water-treatment engineers, EHS and compliance staff, and procurement at industrial and municipal sites.
16 Families of Water Treatment Chemicals#
Water treatment chemicals fall into 16 families by function, from coagulants that destabilize turbidity at rapid mix to ion exchange resins and filter media that remove ions, particles and organics, and each family has its own hub with types, mechanism, dose ranges and standards. Which family does a problem need: scale, corrosion, microbes, oxygen, pH or solids? The table gives each family's job, example chemicals and main systems.
| # | Family | What it does | Example chemicals | Main systems |
|---|---|---|---|---|
| 1 | coagulants for water treatment | destabilize turbidity, color and natural organic matter at rapid mix | aluminum sulfate (alum), polyaluminum chloride, aluminum chlorohydrate, ferric chloride, polyDADMAC | drinking water, wastewater, membrane pretreatment |
| 2 | flocculants for water treatment | bridge destabilized particles into large, settleable floc | polyacrylamide (cationic, anionic, emulsion and dry grades) | clarification, sludge dewatering |
| 3 | scale inhibitors | hold scale-forming salts in solution below their precipitation threshold | HEDP, ATMP, PBTC, DTPMP, polymer inhibitors | cooling towers, boilers |
| 4 | phosphates in water treatment | control corrosion and sequester iron and manganese; boiler internal treatment | orthophosphates, polyphosphates, blended phosphates | drinking-water distribution, boilers |
| 5 | corrosion inhibitors for water treatment | protect steel and copper alloys | zinc, silicate, molybdate, nitrite, azoles, filming amines | cooling towers, closed loops |
| 6 | oxygen scavengers for boiler water | remove dissolved oxygen from boiler feedwater | sodium sulfite, carbohydrazide, DEHA, hydrazine | boilers |
| 7 | neutralizing amines for condensate treatment | neutralize carbon dioxide in steam condensate | cyclohexylamine, morpholine, DEAE | steam and condensate systems |
| 8 | biocides for water treatment | control bacteria, algae and biofilm (non-oxidizing) | isothiazolinone, glutaraldehyde, DBNPA | cooling towers, membranes, wastewater |
| 9 | oxidants and oxidizing biocides | disinfect and oxidize | chlorine, sodium hypochlorite, chlorine dioxide, chloramine, bromine, ozone, peroxygens, permanganate | drinking water, cooling towers, wastewater |
| 10 | pH adjustment chemicals | raise or lower pH and alkalinity | sulfuric acid, hydrochloric acid, caustic soda, lime, soda ash, carbon dioxide | all systems |
| 11 | dechlorination chemicals | remove residual chlorine before discharge or membranes | sodium bisulfite, sodium metabisulfite, sodium thiosulfate | wastewater effluent, RO feed |
| 12 | chelating agents in water treatment | bind hardness and metal ions | EDTA, GLDA, MGDA, gluconate | boiler internal treatment, chemical cleaning |
| 13 | defoamers and antifoams | knock down and prevent foam | silicone and non-silicone defoamers | wastewater aeration, evaporators |
| 14 | descaling and chemical cleaning agents | dissolve scale and deposits off-line | inhibited acids, citric acid, sulfamic acid, chelants | boilers, heat exchangers, membranes |
| 15 | ion exchange resins for water treatment | exchange hardness and other ions | cation, anion, mixed-bed and selective resins | softening, demineralization, dealkalization |
| 16 | adsorbents and filter media | adsorb organics and filter particles, iron, manganese and fluoride | granular and powdered activated carbon, greensand, activated alumina, anthracite, sand | drinking water, industrial pretreatment |
Membrane antiscalants and cleaners sit on the application side, because every RO chemical is defined by the membrane use.
Water Treatment Chemicals by Application: 7 Systems#
Water treatment chemicals are combined into programs for 7 systems: cooling towers, boilers, reverse osmosis membranes, wastewater, drinking water, closed loops and produced water, and each program pairs several families against the system's scale, corrosion, fouling, microbial and compliance risks. Each row names the core chemistries and one control number the program is run to.
| # | Application | What goes wrong | Program core (families) | One control number |
|---|---|---|---|---|
| 1 | cooling tower water treatment | scale, corrosion, biofouling, Legionella | scale and corrosion inhibitors, oxidizing and non-oxidizing biocides, blowdown control | evaporation about 1 % of recirculation per 10 °F (5.6 °C) of range |
| 2 | boiler water treatment | oxygen pitting, scale, carryover, condensate corrosion | oxygen scavengers, internal treatment (phosphate, chelant, polymer), neutralizing amines | food-contact steam caps (21 CFR 173.310): cyclohexylamine 10 ppm, DEAE 15 ppm, morpholine 10 ppm in steam, excluding steam that contacts milk and milk products |
| 3 | reverse osmosis and membrane chemicals | scaling, fouling, biofouling, oxidation of the membrane | antiscalants, dechlorination, cleaners, membrane biocides | polyamide membranes tolerate below 0.1 mg/L (ppm) free chlorine |
| 4 | wastewater treatment chemicals | solids, phosphorus, metals, sulfide odor, foam, discharge limits | coagulants, flocculants, precipitants, oxidants, dechlorination, defoamers | 0.87 mg Al or 1.80 mg Fe per mg P (stoichiometric, 1:1 molar) |
| 5 | drinking water treatment chemicals | turbidity, pathogens, disinfection byproducts, lead and copper release | coagulants, disinfectants, pH adjusters, corrosion-control phosphates, fluoridation chemicals | combined filter effluent at or below 0.3 NTU in at least 95 % of monthly measurements, never above 1 NTU (40 CFR 141.173) |
| 6 | closed loop water treatment | corrosion, microbial growth, glycol degradation | nitrite, molybdate, azoles, inhibited glycol | carbon steel corrosion at or below 0.2 mpy (0.005 mm/y) rated "excellent" (closed-loop corrosion bands) |
| 7 | produced water treatment chemicals | oil and grease, solids, scale | coagulants, flocculants, water clarifiers, scale inhibitors | offshore oil and grease 42 mg/L daily maximum, 29 mg/L 30-day average (40 CFR 435.13, BAT) |
Programs and problem nodes, such as Legionella control, boiler feedwater, RO cleaning and phosphorus removal, sit under each system, all listed on the index of industrial water treatment chemical programs by application.
Water Treatment Chemical Database: Every Chemical by CAS, Function and NSF/ANSI/CAN 60 Status#
The water treatment chemical database gives every chemical with its own page, such as aluminum sulfate, ferric chloride, sodium hypochlorite, HEDP and DEHA, with its CAS number, function, systems and NSF/ANSI/CAN 60 status in one filterable list.
Search by CAS number, function or certification in the water treatment chemical database.
Key Values in Water Treatment: 15 Limits, Ratios and Conversions#
Fifteen values recur across water treatment programs, from the 4.0 mg/L (ppm) as Cl2 maximum residual disinfectant level for chlorine (40 CFR 141.65) to the 8.34 factor that turns a dose in mg/L and a flow in MGD into lb/day of chemical. Which of them are enforceable limits, and which are design ratios? The table marks each value's type, basis and instrument.
| # | Value | Figure and basis | Type | Instrument and date | Owner page |
|---|---|---|---|---|---|
| 1 | Maximum residual disinfectant level | chlorine and chloramines 4.0 mg/L as Cl2; chlorine dioxide 0.8 mg/L as ClO2 (running annual average) | US federal limit (MRDL, not an MCL) | 40 CFR 141.65 | drinking water disinfection |
| 2 | Disinfection byproduct MCLs | TTHM 0.080 mg/L and HAA5 0.060 mg/L as LRAA; bromate 0.010 mg/L; chlorite 1.0 mg/L | US federal limit | 40 CFR 141.64 (Stage 2 DBPR) | disinfection byproducts rules |
| 3 | Lead and copper action levels | lead 0.010 mg/L (90th percentile) from 2027-11-01, 0.015 mg/L until then; copper 1.3 mg/L | action level, not an MCL | 40 CFR 141.80 as amended by LCRI (89 FR 86418, 2024-10-30) | Lead and Copper Rule |
| 4 | Fluoride | MCL and MCLG 4.0 mg/L; SMCL 2.0 mg/L; US PHS optimal 0.7 mg/L (2015, a recommendation, not a limit) | US federal limit + recommendation | 40 CFR 141.62; 40 CFR 143.3 | water fluoridation chemicals |
| 5 | PFAS MCLs | PFOA and PFOS 4.0 ng/L each; PFHxS, PFNA and HFPO-DA 10 ng/L each plus Hazard Index 1; compliance 2029-04-26; EPA proposals of 2026-05-18 pending, not final | US federal limit (final) + pending proposals | 89 FR 32532 (2024-04-26); 40 CFR 141.61(c) | PFAS removal in drinking water treatment |
| 6 | EU chlorate and chlorite | 0.25 mg/L each; 0.70 mg/L where chlorine dioxide or another chlorate-generating disinfection is used; binding from 2026-01-12 | EU parametric value | Directive (EU) 2020/2184 | EU Drinking Water Directive 2020/2184 |
| 7 | NSF/ANSI/CAN 60 maximum use level | product-specific, as product, total across all application points; aluminum coagulant listings: aluminum in finished water not to exceed 2 mg/L (a listing condition, not an EPA limit) | certification condition | NSF listings, 2026-10-20 | NSF/ANSI/CAN 60 |
| 8 | Polymer monomer limits | acrylamide 0.05 % monomer dosed at 1 ppm; epichlorohydrin 0.01 % dosed at 20 ppm; annual certification to the State | US treatment technique, not an MCL | 40 CFR 141.111 | flocculant and coagulant hubs (Table 1) |
| 9 | Feed-rate formula | lb/day = dose (mg/L) x flow (MGD) x 8.34 / purity (as a fraction) | design factor | operator feed arithmetic | chemical dosage calculator |
| 10 | Hardness and phosphate conversions | 1 gpg = 17.1 mg/L as CaCO3; mg/L as PO4 x 0.326 = mg/L as P; ppm equals mg/L only at a density of about 1 | conversion | unit arithmetic | water hardness |
| 11 | Hypochlorite strength | 12.5 trade % = 125 g/L available chlorine = about 11.2 wt % NaOCl (trade % = g/L available chlorine / 10) | conversion | strength tables | sodium hypochlorite in water treatment |
| 12 | RO dechlorination ratio | sodium metabisulfite 1.34 mg and sodium bisulfite 1.47 mg per mg Cl2 in theory; about 3 mg per mg in practice | design factor | membrane manufacturer guidance | RO pretreatment chemistry |
| 13 | Cooling tower water balance | blowdown = E / (C - 1); make-up = E x C / (C - 1) (E = evaporation, C = cycles) | design factor | cooling-tower mass balance | cooling tower blowdown |
| 14 | Boiler blowdown | blowdown as % of feedwater = 100 / cycles of concentration (a percent of feedwater, not of steam) | design factor | boiler mass balance | boiler blowdown |
| 15 | Chlorine process-safety thresholds | 2,500 lb (1,134 kg) under EPA RMP; 1,500 lb (680 kg) under OSHA PSM | US federal threshold | 40 CFR 68.130 Table 1; 29 CFR 1910.119 Appendix A | EPA RMP and OSHA PSM |
Regulatory values as of 2026-10-20; pending proposals are labelled as proposals. NSF values: NSF listings, 2026-10-20.
Water Treatment Chemistry Concepts and Calculators#
Seven chemistry concepts explain how water treatment chemicals act, from coagulation and the jar test to scale formation, the Langelier Saturation Index, cycles of concentration, chlorination and breakpoint chlorination, and the calculators turn them into doses and limits. The LSI is the measured pH minus the saturation pH, so a positive value signals calcium carbonate deposition.
These ideas form the full set of water treatment chemistry concepts, which covers scaling, corrosion, disinfection and coagulation. The table below pairs each concept or tool with the question it answers.
| # | Concept or tool | What it answers | Kind |
|---|---|---|---|
| 1 | coagulation and flocculation in water treatment | how particles are destabilized and grown into floc | concept |
| 2 | jar test | bench-scale choice of coagulant and dose | concept |
| 3 | scale formation in water systems | calcium carbonate, sulfate, silica and phosphate scale | concept |
| 4 | Langelier Saturation Index | LSI = pH (measured) - pHs; Ryznar, Puckorius and Stiff-Davis indices | concept |
| 5 | cycles of concentration | ratio of dissolved solids in blowdown to make-up | concept |
| 6 | water chlorination chemistry | HOCl, OCl- and pH | concept |
| 7 | breakpoint chlorination | chlorine demand and the breakpoint curve | concept |
| 8 | CT values for disinfection | CT = residual C (mg/L) x contact time T10 (min) | concept |
| 9 | water treatment chemical compatibility | incompatible mixtures at the plant | concept |
| 10 | Langelier Saturation Index calculator | LSI, RSI, PSI from water analysis | calculator |
| 11 | cooling tower water balance calculator | cycles, blowdown, make-up, evaporation | calculator |
| 12 | CT value calculator | CT and log inactivation | calculator |
Every tool, from the LSI calculator to the quote forms, is on the page of water treatment calculators and quote tools.
Regulations and Standards for Water Treatment Chemicals#
Water treatment chemicals are governed in 4 layers: NSF/ANSI/CAN 60 certification, AWWA and CEN product standards, US rules for drinking water, discharges and food-contact steam, and EU rules for drinking water and biocides. The 4 layers are listed below.
- Product certification: NSF/ANSI/CAN 60 is required in the regulations of 48 of 50 US states (NSF, 2019); filter media and ion exchange resins fall under NSF/ANSI/CAN 61.
- Product standards: 49 AWWA B-series standards, from ANSI/AWWA B100-25 (granular filter media) to B703-24 (fluorosilicic acid), and the EN standards for drinking water treatment chemicals from CEN/TC 164.
- US rules: Safe Drinking Water Act rules in 40 CFR 141, NPDES and 40 CFR 403 pretreatment for discharges, and 21 CFR 173.310 for boiler water additives in food-contact steam.
- EU rules: Directive (EU) 2020/2184 (Article 12 for treatment chemicals and filter media) and the EU Biocidal Products Regulation, which approves sodium hypochlorite, calcium hypochlorite and chlorine for drinking-water disinfection (PT5) from 2019-01-01 to 2028-12-31.
US EPA also keeps 47 chemical supply-chain profiles, 36 of them for chemicals used in water treatment (page updated 2026-06-30). Rules, editions and pending changes are tracked on water treatment regulations and standards.
Water Treatment Companies and Chemical Suppliers#
Water treatment chemicals are bought in 2 ways: as a treatment program from a provider who supplies the chemicals and runs testing, dose control and reporting, or as chemicals delivered to a specification such as NSF/ANSI/CAN 60 and an AWWA standard by a manufacturer or distributor.
Program providers, service models and quotes are compared under water treatment companies.
Grand View Research estimates the global market at USD 35.8 billion in 2025; segments are set out under water treatment chemicals market.
Manufacturers, blenders and distributors are compared on water treatment chemical suppliers, with a regional view of water treatment chemical manufacturers in India.
How WaterTreatmentChemicals.net Sources and Checks Every Value#
Every value on WaterTreatmentChemicals.net comes from a primary source, such as the eCFR, the Federal Register, NSF listings, AWWA and CEN standards, EPA guidance, WHO guidelines and EUR-Lex, and carries its instrument, edition or check date in the sentence. Supplier figures are labelled as supplier figures, and a value that cannot be confirmed from a primary source is left out.
Who runs the reference and why it stays vendor-neutral is explained on about WaterTreatmentChemicals.net.
Beyond the Chemical Program: Water Treatment Processes, Parameters, Equipment and News#
Three outer sections support the chemical program: treatment processes stage by stage, water quality parameters such as alkalinity, hardness and turbidity, and equipment such as dosing pumps and cooling towers.
Every stage and its chemicals are set out under water treatment process; water quality parameters and water treatment equipment cover the measurements and hardware.
Rule changes, supply disruptions and new technology appear in water treatment chemicals news.
What are the top 10 chemicals used in water treatment?#
No fixed top 10 exists, because the chemicals used depend on the system: utilities rely on coagulants, chlorine-based disinfectants, pH adjusters and corrosion-control phosphates, while boilers and cooling towers rely on scale and corrosion inhibitors, oxygen scavengers and biocides. The overview of water treatment chemicals lists every family with its most used chemicals.
Does WaterTreatmentChemicals.net sell water treatment chemicals?#
No: WaterTreatmentChemicals.net sells no chemical and no service; quote requests are passed to independent providers and suppliers, and no partner pays for placement in editorial content.
Which water uses does WaterTreatmentChemicals.net not cover?#
WaterTreatmentChemicals.net covers only chemicals and media dosed or specified in industrial, municipal and utility water systems, so it never covers consumer or non-water uses. The 4 excluded areas are listed below.
- No pool, spa, hot-tub, pond or aquarium chemistry
- No household or point-of-use water treatment
- No emergency drinking-water treatment
- No medical, food, cosmetic or agricultural uses of the same chemicals
How current are the values on WaterTreatmentChemicals.net?#
Each regulatory value states its instrument and date, each standard its full edition and each certification value its listing date, such as "NSF listings, 2026-10-20", so the reader sees how current the value is.
How do I contact the editors or report a correction?#
Corrections and questions go to the editors through the contact form, and corrected values carry the new check date on the page.
The form is on contact WaterTreatmentChemicals.net, and email reaches editorial@watertreatmentchemicals.net.