A guide to potassium permanganate, what it is, how it's dosed in water treatment, and how it's supplied, from a US-based distributor.
Potassium permanganate (KMnO4, CAS 7722-64-7) is a strong oxidizing agent supplied as purple-black crystals. Its largest use is water treatment, oxidizing dissolved iron and manganese and controlling taste, odor and hydrogen sulfide. Stratus Chemical supplies free-flowing grade suitable for NSF/ANSI 60 drinking water treatment applications, with COA and SDS provided.
| Property | Value |
|---|---|
| Chemical name | Potassium permanganate |
| CAS number | 7722-64-7 |
| Molecular formula | KMnO4 |
| Molecular weight | 158.03 g/mol |
| EC / EINECS | 231-760-3 |
| Synonyms | Permanganate of potash, Condy's crystals |
| Appearance | Dark purple to purple-black crystals with a metallic lustre |
| Drinking water | Suitable for NSF/ANSI 60 drinking water treatment applications |
| Transport | Class 5.1 oxidizer, per SDS |
| Grades supplied | Free-flowing technical grade |
| Packaging | Drums and pails |
Potassium permanganate is an inorganic salt of manganese in its +7 oxidation state, supplied as dark purple crystals that dissolve to give the characteristic intense purple solution. It is a strong oxidizing agent, and essentially all of its industrial uses exploit that property.
Its practical advantage over many alternatives is that it oxidizes cleanly. The manganese is reduced to insoluble manganese dioxide, which is filtered out, so it doesn't leave problematic dissolved residues or form the halogenated byproducts that chlorine-based oxidants can. It is manufactured from potassium hydroxide and manganese dioxide, and stores essentially indefinitely when kept dry and sealed.
Water treatment is the dominant application for potassium permanganate in the United States, accounting for more than half of domestic consumption. It is typically dosed at the head of the plant, ahead of filtration.
Dissolved ferrous iron and manganese pass straight through filters and cause the rusty and black staining that generates customer complaints. Potassium permanganate oxidizes both to insoluble oxides that filter out. Theoretical demand is approximately 0.94 mg KMnO4 per mg of iron and 1.92 mg per mg of manganese. Actual dose is higher and is always set by jar testing, because organic matter and other reducing species in the raw water compete for the oxidant. Where the raw water can be aerated, or already carries an oxidant, granular manganese dioxide is the alternative route to the same result, combining oxidation and filtration in a single vessel.
Manganese greensand filters are regenerated with potassium permanganate, restoring the oxidizing coating that catalyses iron and manganese removal. This is a steady, repeat-volume application.
Oxidizes the organic compounds responsible for earthy and musty taste, including those produced during algal blooms.
Oxidizes H2S in both drinking water and wastewater collection systems, addressing rotten-egg odor and the corrosion of concrete and metal that sulfide causes.
Used as a pre-oxidant to reduce the organic precursors that form trihalomethanes when chlorine is added downstream.
Dose is always established by jar testing on the actual water. Overdosing leaves pink or red water at the tap, a highly visible failure that generates immediate complaints, so plants target a slight residual that is consumed before the clearwell.
| Factor | KMnO4 | Chlorine | Chlorine dioxide | Ozone |
|---|---|---|---|---|
| Manganese oxidation | Very effective | Slow | Effective | Very effective |
| Halogenated byproducts | No | Yes | Chlorite / chlorate instead | No |
| Residual disinfection | No | Yes | Yes | No |
| On-site generation | Not required | Not required | Required | Required |
| Capital cost | Low, a dry feeder | Low | Higher | Highest |
| Main drawback | Pink water if overdosed; oxidizer handling | Byproducts, taste | Generation complexity | Capital and power |
Potassium permanganate is generally chosen where manganese is the problem, where pre-oxidation is needed without adding halogenated byproduct precursors, and where capital budget rules out ozone or chlorine dioxide generation. It provides no residual disinfection, so it is used alongside a disinfectant rather than instead of one.
Stratus supplies free-flowing technical grade, which is treated to resist caking so it feeds reliably through volumetric and gravimetric dry chemical feeders. This matters in water treatment, where caking causes feeder bridging and missed dose.
Potassium permanganate is a strong oxidizer. It does not burn, but it supplies oxygen that makes other materials burn readily, and in some contact cases ignites them directly.
Potassium permanganate is a DEA List II regulated chemical. Distributors are subject to customer identification, recordkeeping and reporting requirements on regulated transactions. COA and SDS are provided with every shipment.
Potassium permanganate is used primarily in water treatment, to oxidize dissolved iron and manganese, control taste and odor, oxidize hydrogen sulfide and regenerate manganese greensand filters. Other uses include air and gas purification, environmental remediation, aquaculture, produced water treatment and chemical synthesis.
The CAS number for potassium permanganate is 7722-64-7. Its molecular formula is KMnO4 and its molecular weight is 158.03 g/mol. It is also known as permanganate of potash.
Theoretical demand is approximately 0.94 mg of potassium permanganate per mg of dissolved iron, and 1.92 mg per mg of dissolved manganese. Actual dose is higher and must be set by jar testing on the specific water, because organic matter and other reducing compounds compete for the oxidant.
The purple-pink color is the permanganate ion itself. If more is dosed than the water's oxidant demand consumes, the excess remains and the water appears pink or red at the tap. Plants target a small residual that is fully consumed before treated water leaves the plant.
Yes. Stratus Chemical supplies free-flowing potassium permanganate suitable for NSF/ANSI 60 drinking water treatment applications. It is used by municipal and industrial water plants for iron and manganese removal, taste and odor control and greensand regeneration.
Yes. Potassium permanganate is classified as a Class 5.1 oxidizer for transport and is corrosive to skin. It does not burn but intensifies the combustion of other materials, and contact with glycerin or other organics can cause ignition. Store it dry and separated from combustibles, acids and reducing agents.
Free-flowing potassium permanganate is treated to resist caking so that it feeds reliably through volumetric and gravimetric dry chemical feeders. This matters in water treatment, where caking causes feeder bridging and missed dose.
Yes. Potassium permanganate is a DEA List II regulated chemical. Distributors are subject to customer identification, recordkeeping and reporting requirements on regulated transactions above defined thresholds.
Looking for related products? See manganese dioxide for filter beds, caustic soda, sodium gluconate, the full product range, the water treatment range, or request a quote.
Tell us the grade, form, and volume. We'll respond with pricing and availability within one business day.
Request a Quote →