Potassium Permanganate in Water Treatment: Uses, Dosage, Specifications and Safety

Potassium permanganate (KMnO4, CAS 7722-64-7) is a manganese(VII) oxidant dosed ahead of filtration to oxidize dissolved iron, manganese, hydrogen sulfide and taste and odor compounds. Utilities feed 0.3 to 5 mg/L as KMnO4, against a theoretical demand of 0.94 mg per mg of iron(II) and 1.92 mg per mg of manganese(II) (NHMRC, Australian Drinking Water Guidelines).

Most NSF/ANSI/CAN 60 listings set a maximum use level of 50 mg/L as product, on condition that finished water holds no more than 0.05 mg/L manganese (NSF listings, 2026-10-21). Potassium permanganate is one of the oxidants in this reference of water treatment chemicals, documented with the same identity, dose and compliance fields.

The identity card below summarizes the defining attributes.

Every value on this page is checked against primary sources (NHMRC, Health Canada, NSF listings, eCFR, EUR-Lex, NIOSH); see our methodology and fact-checking process.

What Is Potassium Permanganate?#

Potassium permanganate is an inorganic permanganate salt whose manganese sits in the +7 oxidation state and is reduced to insoluble manganese dioxide (MnO2) when it oxidizes a contaminant. That reduction gives it three functions: oxidant, filter-media regenerant and limited disinfectant.

The US EPA counts potassium permanganate among the 36 chemicals used in water treatment in its Water Treatment Chemical Supply Chain Profiles.

Crystals, powder or solution: which form do plants handle?#

Plants buy free-flowing crystals of at least 97 % KMnO4 and dissolve them on site into a dilute stock solution. The Suez Water Handbook gives about 3 g/L (0.3 %) as a typical stock strength, and NHMRC notes that solutions above 2.5 % usually need heating to dissolve.

The table below compares the crystal grades and the stock solution.

How Does Potassium Permanganate Oxidize Iron, Manganese and Sulfide?#

Potassium permanganate takes electrons from dissolved iron(II), manganese(II) and sulfide and becomes manganese dioxide solids, which the filters remove together with the oxidized iron and manganese. For manganese the reaction is 3 Mn2+ + 2 MnO4- + 4 OH- → 5 MnO2 + 2 H2O, and the MnO2 formed also adsorbs further Mn2+ and natural organic matter (NHMRC).

Oxidation is most effective at pH 8.5 or higher (NHMRC), and dissolved organic carbon slows it.

How fast does permanganate oxidize dissolved manganese?#

Permanganate oxidizes 0.25 mg/L of dissolved manganese within 60 seconds at 105 % of the stoichiometric dose, at pH 5.5 to 9, 25 °C (77 °F) and dissolved organic carbon (DOC) below 1 mg/L (Health Canada, 2019). At 10 mg/L DOC it takes 1 to 2 minutes, and 2 to 4 minutes of reaction time suffices for most plants.

Where Is Potassium Permanganate Used in Water Treatment?#

Potassium permanganate is used in 2 systems, drinking water and municipal wastewater, for 6 jobs: iron and manganese oxidation, taste and odor control, color removal, DBP precursor pre-oxidation, hydrogen sulfide oxidation and filter-media regeneration.

The table below compares those uses.

Drinking water: iron and manganese removal#

Utilities feed potassium permanganate at the head of the plant, near the intake, so that all permanganate is reduced to MnO2 before the filters (NHMRC). Organic matter raises the demand above the stoichiometry, so the jar test sets the dose. Oxidant choice, media and biological filters are compared under iron and manganese removal.

The US EPA UV disinfection toolkit (EPA 815-B-21-007, 2022) notes that chlorine with iron and manganese present fouls UV sleeves, and that permanganate upstream of sedimentation reduces this fouling.

Taste, odor, color and disinfection byproduct precursors#

Potassium permanganate serves as a pre-oxidant for taste, odor and color compounds. The US secondary standard for odor is 3 threshold odor numbers (40 CFR 143.3). Geosmin, MIB and carbon programs are covered under taste and odor control.

Permanganate also pre-oxidizes THM and HAA precursors; the Stage 2 rule limits TTHM to 0.080 mg/L and HAA5 to 0.060 mg/L as locational running annual averages (40 CFR 141.64). Precursor removal and the Stage 2 limits are explained under disinfection byproducts.

Can potassium permanganate be used for disinfection?#

Only in a limited way: its role is oxidation, and disinfection is a limited, secondary function. Its listed functions put oxidation and media regeneration first. Primary and secondary disinfectants are compared under drinking water disinfection.

Regeneration of greensand and manganese oxide filter media#

Potassium permanganate restores the MnO2 surface of greensand and manganese oxide media, either continuously ahead of the filter or in periodic batches. The KMnO4 demand estimate is 1 x Fe + 2 x Mn in mg/L, and excess permanganate leaves as pink water. The GreensandPlus data sheet (supplier figure) regenerates new media for at least 4 hours with 4 oz KMnO4 per ft³ (about 4.0 kg/m³). Regeneration modes and loading rates are on manganese greensand.

Wastewater: hydrogen sulfide, odor and color#

Municipal wastewater plants use potassium permanganate for hydrogen sulfide and odor control, and industrial plants use it for color removal, according to the Carus applications list. Permanganate is compared with iron salts, nitrate and peroxide under hydrogen sulfide and odor control chemicals.

How Is the Potassium Permanganate Dose Calculated and Fed?#

The potassium permanganate dose is the iron and manganese demand plus the organic demand found in the jar test, converted with lb/day = mg/L x MGD x 8.34 / purity (Florida DEP operator formulas); in metric, kg/d = mg/L x m³/d / 1,000.

The table below is a worked example (calculated) with every input stated.

How much potassium permanganate per mg/L of iron and manganese?#

Potassium permanganate demand is 0.94 mg per mg of iron(II) and 1.92 mg per mg of manganese(II), as KMnO4 (NHMRC; Health Canada rounds the manganese ratio to 1.9).

Each mg of manganese consumes 1.2 mg alkalinity as CaCO3 and yields 2.6 mg MnO2; each mg of iron consumes 1.5 mg and yields 2.4 mg Fe(OH)3 (NHMRC). A 97 % product needs the KMnO4 dose divided by 0.97. For other flows, the chemical dosage and feed rate calculator converts any KMnO4 dose to kg/d, lb/day and pump settings.

Which feed systems and stock solution strengths are used?#

Most plants dissolve the crystals to a stock of about 3 g/L and meter it as a liquid; at 10 MGD that is about 1,000 L/h (264 gal/h). Recommended Standards for Water Works (2022 edition, 5.3 g) sets the feeder minimum operating point at 20 % of the maximum feed rate, or 10 % for pumps with two independent adjustments. Dry feeders, dissolving tanks and metering pumps are described under chemical feed systems.

How Is Permanganate Dosing Controlled? Pink Water, Residual Manganese and Test Interference#

Permanganate dosing is controlled by the color of the filter influent and by the manganese concentration of the finished water. Finished water shows no pink color, manganese below 0.02 mg/L avoids complaints (NHMRC), and Health Canada sets a goal of 0.015 mg/L or less.

The four control checks are listed below.

• Filter-influent color: a visual pink check at the filter influent.
• Finished-water manganese: at or below 0.05 mg/L, the NSF/ANSI/CAN 60 listing condition.
• Chlorine test interference: permanganate reads as chlorine in free and total chlorine tests.
• Jar test: repeated when raw-water iron, manganese or organics change.

Free and total chlorine methods are explained under chlorine residual.

How is potassium permanganate dosed in a jar test?#

A jar test doses the stock solution by volume: 1.9 mg/L in a 2 L jar needs 3.8 mg of KMnO4, which is 1.27 mL of a 3 g/L stock (calculated). Mixing and reading the jars follow the jar test procedure.

What Is Potassium Permanganate Incompatible With?#

Potassium permanganate is a strong oxidizer that can explode on contact with organic or other readily oxidizable substances, dry or in solution (HSDB 1218). The three incompatibility groups are listed below.

• Organic and readily oxidizable materials: glycerol in contact with permanganate may explode.
• Reducing agents: they react with permanganate.
• Activated carbon: oxidants and carbon consume each other, so plants feed powdered activated carbon (PAC) at a separate point.

Which Standards Cover Potassium Permanganate? NSF/ANSI/CAN 60, AWWA B603 and EN 12672#

Three documents cover potassium permanganate for drinking water: NSF/ANSI/CAN 60 for health effects, ANSI/AWWA B603-23 for North American product requirements and EN 12672 for European product requirements.

The table below compares them.

What is the NSF/ANSI/CAN 60 maximum use level for potassium permanganate?#

There is no single limit: the maximum use level is product-specific, and 81 of the 83 product-function rows list 50 mg/L as product (NSF listings, 2026-10-21). The listings cover 16 companies and 72 products (company and trade designation); two diluted solutions list 2,500 and 1,250 mg/L. Each MUL is the total across all application points.

Each listing requires finished-water manganese of 0.05 mg/L or less, and Section 6.3.4, added in the 2024 edition, tests permanganates for manganese. NSF/ANSI/CAN 60 is required in 49 US states (NSF survey of ASDWA members). MULs and state adoption are covered under NSF/ANSI/CAN 60 certification.

What do AWWA B603 and EN 12672 specify?#

ANSI/AWWA B603-23 Permanganates is the North American product standard for potassium and sodium permanganate. B603 sits in the taste and odor group of the AWWA B-series standards.

EN 12672 sets the European grades (97.5 % and 98.5 % KMnO4) and impurity limits of 20 mg/kg arsenic, 50 mg/kg each of cadmium, chromium, nickel, lead, antimony and selenium, and 10 mg/kg mercury.

What Is the Regulatory Status of Potassium Permanganate in Drinking Water Treatment?#

Potassium permanganate is regulated through the manganese it can leave in finished water, through NSF/ANSI/CAN 60 certification and through its oxidizer class in transport, not by a chemical-specific drinking water limit (status 2026-10-22).

The table below compares the instruments by jurisdiction.

Pre-oxidation beside coagulation and disinfection is shown under drinking water treatment chemicals.

Is there an EPA MCL for manganese?#

No: the US value of 0.05 mg/L for manganese is a non-enforceable secondary standard (40 CFR 143.3), not an MCL. The same 0.05 mg/L is the NSF/ANSI/CAN 60 listing condition for permanganate. Health Canada sets a maximum acceptable concentration of 0.12 mg/L and an aesthetic objective of 0.02 mg/L (2019).

How Should Potassium Permanganate Be Handled and Stored Safely?#

Potassium permanganate is an oxidizing solid with the harmonised CLP Annex VI classification H272, H302, H361d, H400 and H410 (index 025-002-00-9) and the signal word "Danger", stored dry in closed containers away from organic material. Its pictograms are GHS03 (flame over circle), GHS07, GHS08 and GHS09.

The Suez Water Handbook specifies closed steel or plastic containers at ambient temperature. PPE and spill response follow the supplier's SDS. Containment and materials by chemical are covered under chemical storage tanks.

The table below summarizes storage and handling.

What does a potassium permanganate safety data sheet (SDS) cover?#

A potassium permanganate SDS covers one product from one supplier, and notified classifications in ECHA C&L add H314 (48.5 % of 472 notifications), H373 (33.7 %) and H318 (30.9 %) beside the harmonised codes. The four checks for a buyer are listed below.

1. Confirm the harmonised codes in section 2.
2. Check UN1490, class 5.1, packing group II in section 14.
3. Compare section 8 with OSHA PEL C 5 mg/m³ as Mn.
4. Read section 10 for organics and glycerol.

Customs documents use HS 2841.61 (US HTS 2841.61.00.00).

What Are the Alternatives to Potassium Permanganate?#

Five alternatives replace potassium permanganate for iron and manganese oxidation, differing in demand per mg of manganese and in the by-product they leave.

The table below compares them.

Potassium permanganate vs sodium permanganate#

Sodium permanganate (CAS 10101-50-5) runs the same Mn(VII) to MnO2 chemistry but arrives as a 20 % (CARUSOL) or 40 % (LIQUOX) liquid, which avoids dissolving crystals and handling dust. Its demand is 1.72 mg per mg Mn(II) and 0.84 mg per mg Fe(II) (calculated from the KMnO4 ratios), and most NSF listings set 176 mg/L for the 20 % grade and 88 mg/L for the 40 % grade, as product (NSF listings, 2026-10-21). Liquid grades and their listings are on sodium permanganate.

Potassium permanganate vs chlorine dioxide and ozone#

Chlorine dioxide needs 2.45 mg per mg of manganese(II), and ozone 0.87 mg, against 1.9 mg for potassium permanganate (Health Canada, 2019). Chlorine dioxide leaves chlorite, which has an MCL of 1.0 mg/L, and its residual is capped by an MRDL of 0.8 mg/L as ClO2 (40 CFR 141.64 and 141.65). Generation, chlorite control and MRDL are covered under chlorine dioxide.

Ozone in practice needs 2 to 5 times its stoichiometric dose, and high ozone doses re-oxidize MnO2 to permanganate, which turns water pink.

Potassium permanganate vs chlorine#

Chlorine needs 1.3 mg of HOCl per mg of manganese(II) in theory and about 4 times that in practice, and it oxidizes manganese effectively only above pH 9 (Health Canada, 2019). At pH 7 and 25 °C it needs 3 hours or more (Knocke et al., 1990). The chlorine residual is capped by an MRDL of 4.0 mg/L as Cl2. Strength, trade % and MUL are covered under sodium hypochlorite.

Potassium Permanganate Grades, Suppliers and Sourcing#

Potassium permanganate for water treatment comes from a small group of permanganate producers and distributors in two grades: free-flowing (97 % or more) and technical (98.5 % or more). Buyers should confirm the NSF/ANSI/CAN 60 listing per trade name and facility. Distributors and producers by region are listed under water treatment chemical suppliers.

The table below lists makers and distributors, alphabetically.

Listed alphabetically; no company is a partner of this site and none pays for inclusion.

How is potassium permanganate priced and quoted?#

Potassium permanganate is quoted by grade, purity and package, and offers compare per kg (lb) of KMnO4 after dividing the product price by the purity. Public procurement records show what buyers paid at a given date and place; they include delivery and local terms and are not a current price.

The City of Fremont, Ohio, US, published 4 bids for potassium permanganate at USD 2.65 to 4.18 per pound in its 2026 Chemicals Bid Tab (publication 2025-11-05). The City of Emporia, Virginia, US, received 4 bids for potassium permanganate (Cairox) in 55 lb pails, 4,000 lb per year, at USD 2.31 to 4.95 per pound (bid opening 2025-06-23, term FY26). Concord, North Carolina, US, received 2 bids for potassium permanganate at USD 4.577 to 4.72 per pound (Bid #2633, bid opening 2024-06-04).

Quote factors are grade, purity, standard, NSF/ANSI/CAN 60 listing, annual quantity, package, freight distance and contract term. Send one specification and request quotes for water treatment chemicals on the same purity basis.

Where Does Potassium Permanganate Sit Among Oxidants for Water Treatment?#

Potassium permanganate is the solid permanganate oxidant beside chlorine, chlorine dioxide, ozone and the peroxygens, used mainly for pre-oxidation rather than disinfection. All oxidant classes are compared under oxidants and oxidizing biocides for water treatment.

Potassium permanganate FAQs#

Why does water turn pink after permanganate treatment?#

Water turns pink when unreacted permanganate passes the filters, from overdosing, from greensand regeneration or from high ozone doses that re-oxidize MnO2. Finished water must show no pink color.

Is potassium permanganate the same as Condy's crystals?#

Yes: Condy's crystals is a historical name for potassium permanganate, as are permanganate of potash and chameleon mineral.

Does potassium permanganate help remove arsenic?#

Yes: permanganate is one of the effective oxidants for arsenic(III), with chlorine, ozone and manganese dioxide media, while aeration is not effective (US EPA). Oxidation before adsorption or coagulation is covered under arsenic removal from drinking water.

Is potassium permanganate a hazardous material in transport?#

Yes: solid potassium permanganate ships as UN1490, class 5.1 oxidizer, packing group II (49 CFR 172.101).