What is Chlorine Dioxide Used For

While Chlorine and Chlorine dioxides are somewhat similar Chlorine and chlorine dioxide are both oxidizing agents and electron receivers. However, chlorine has the capacity to take in two electrons, whereas chlorine dioxide can absorb five. This means that as far as disinfection which is one of the main functions of Chlorine Dioxide ClO2 is 2.6 times more effective than Chlorine. What is chlorine dioxide used for?

Chlorine dioxide (ClO2) is a strong oxidizer & disinfectant used to sterilize & kill pathogenic microbes, fungi, bacteria, & viruses found In Industries like:

  • Drinking H2O
  • Wastewater
  • Air Scrubbers
  • Disinfecting Fogging (Hospitals & Clinics)
  • Food Processing
  • Cruise Ships
  • Oral & skin health
  • Farm Irrigation

Chlorine Dioxide is finding its way around the world as an alternative to Chlorine where Disinfection is needed for Water Treatment It has positives and negatives like all chemicals do.

What is Chlorine Dioxide


Chlorine Dioxide, like Chlorine, Monochloramine, is commonly used as halogenated oxidizing agents used in the disinfection process. These chemical disinfectants are utilized in both the treatment of water and wastewater treatment and for maintaining disinfectant residuals in water distribution systems for known safe practices. The best thing about using Chlorine Dioxide instead of Chlorine is that it does not interact with ammonia or ammonium. It is also very effective in cold temperatures. Contrary to chlorine. chlorine dioxide is effective at a pH of between 5 and 10. 

Chlorine Dioxide ClO2  is listed as a Water additive used to control microbes. Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) Anemia; infants and young children: nervous system effects This parameter set by EPA is 0.8 mg/L. 

By contrast, Chlorine Cl2 is a listed Water additive used to control microbes. Potential Health Effects from Long-Term Exposure Above the MCL Eye/nose irritation; stomach discomfort

Chlorine Dioxide is a small, volatile, and very strong molecule consisting of 1 Chlorine atom and 2 oxygen atoms. Abbreviated to ClO2, Chlorine Dioxide exists as a free radical in dilute solutions. Its a gas at normal pressure and chemical. Its color is similar to Chlorine yellow and greenish and smells like Chlorine. Chlorine Dioxide will decompose with the presence of Ultra Violet light, higher temperatures say greater than 70oC, and higher alkalinity (>pH12). It is a reddish-brown liquid between −59 °C and 11 °C, and bright orange crystals when colder in temperature.

It’s able to transfer oxygen to a variety of substrates while gaining one or more electrons by oxidation-reduction.  When Chlorine Dioxide is added to water for disinfection it’s usually handled as a dissolved gas in solution in water made on-site where it will be used and mixed in a Chlorine Dioxide Generator.

In 1811 it was first discovered by Sir Humphrey Davey. In 1944 was the first commercial application. Used as a biocide/taste and odor control agent in domestic water at Niagara Falls in the USA. Since then it is used in thousands of Municipalities as a control for biological control and disinfection for potable drinking water. Also used in Pulp, Paper, and other industrial industries.


Chlorine Dioxide For Swimming Pools


Microorganisms in polluted swimming pools are normal. Every swimmer adds 1.000.000 to microorganisms to the water. The water itself contains microorganisms, as well. After oxidation, a disinfectant must be added to the water to kill pathogenic microorganisms. Chlorine that is usually added to swimming pools has to meet certain demands to disinfect the water without hurting the people using the pool.

Because of the occupants that are using the pool every day there must a residual that is maintained as part of the main control. This must be done easily so that every person owning a pool can test and maintain the proper parameter that is called for. When too much chlorine is present, it can cause eye and mucous membrane irritation, as a result of chloramine formation. So both pH has to be maintained to keep the Chlorine residual in check or the Chloramines are formed depleting the power of the Chlorine.

Chlorine Dioxide doesn’t have that problem and can work at a wide range of pH that Chlorine can’t. It also won’t break down into the by-products that come with using Chlorine in your swimming pool. The cost is dependent on the cost of the original chemicals (sodium chlorite or sodium chlorate), the chemicals used to change these chemicals into chlorine dioxide, and the generation technique used. There are a lot of people that cannot bear chlorine as a disinfectant in their swimming pool for various health reasons which make Chlorine Dioxide a viable solution.


Is Chlorine dioxide Safe to Ingest


Chlorine was used in place of Chlorine that it was less corrosive and the fact that they did not create trihalomethanes a cancerous by-product of using Chlorine. These dangerous by-products are produced when Chlorine is mixed with water that carries naturally occurring organic waste. It was also found to work better in higher or lower pH water.

It’s EPA registered as a Disinfectant. They consider it more effective than Chlorine against bacteria, cyst, and protozoa fighting Cholera and Dysentery around the world. Chlorine or Chlorine Dioxide is added to drinking water to kill these germs and diseases all through 

When Chlorine Dioxide mixes in water, it will react and forms a chlorite ion, which is also a very reactive chemical. Because chlorine dioxide is very reactive, it is able to kill bacteria and microorganisms in water. About 5% of large water-treatment facilities (serving more than 100,000 persons) in the United States use chlorine dioxide to treat drinking water. An estimated 12 million persons may be exposed in this way to chlorine dioxide and chlorite ions. In communities that use chlorine dioxide to treat drinking water, chlorine dioxide and its by-product, chlorite ions, may be present at low levels in tap water.

Chlorine Dioxide For Water Treatment


The main reason for Wastewater Treatment is for the removal of pathogenic microorganisms. Secondarily, wastewater discharge should not contain Chlorine compounds with environmental health impacts. While having a Chlorine residual is a desirable result in Water Treatment it’s not in Wastewater Treatment. Chlorine can have an adverse effect on receiving a stream that can hurt the environment. Chlorine residual should be always maintained as a low reading in Wastewater Treatment Plants.

Chorine inactivates bacteria and viruses but it can also lead to the formation of disinfection by-products (DBPs) through reaction with organic compounds. In wastewater, the high concentration of organic components leads to a higher formation potential of DBPs than in drinking water disinfection. Chlorine can also form other byproducts combined with Ammonia and at different pH levels.  Trihalomethanes (THMs) and haloacetic acids (HAAs), two groups of halogenated compounds with adverse human health effects.  using chlorine as a disinfectant. Having operated large Wastewater facilities, a simple parameter such as Chlorine and pH could be the most vital because of the by-products created by Disinfection.


Chlorine Dioxide Generator


Chlorine Dioxide Generators –distribute Chlorine dioxide is a reactive oxidizing gas that is readily soluble in water and located on-site in the treatment process. Even dilute solutions (10 ppm) of chlorine dioxide have a characteristic yellow color. ChlChlorine dioxide generators feed and mix precursor chemicals and provide sufficient residence time for the generation reaction to go to completion. The required residence time varies from less than a minute for hypochlorous (Cl2 or HCl-NaOCl) generation to 15 minutes for an acid generation.

Generators differ predominantly in the type of chemical feed systems they employ. Chlorine dioxide generators have to be able to feed and to mix precursor chemicals and provide sufficient residence time for the reaction to take place. Gas-phase Chlorine Dioxide
concentrations in excess of 10%, like ozone, can decompose explosively. This is the reason that chlorine dioxide must be generated at its point-of-use.

Three types of designs are used: 1) vacuum feed systems, which pull fluids into the generator; 2) pressure feed systems, which push fluids into the generator; and 3) a combination of pressure and vacuum feed systems. While liquid chemicals (acid, sodium hypochlorite, and sodium chlorite solutions) can use any type of feed system, chlorine gas must be added by a vacuum (or combination) feed.

These delivery systems are similar to Chlorine Gas that is used for disinfection at Water and Wastewater treatment facilities. The Chlorine is or uses to be kept in large 1 or 2-ton containers that controlled and feed by these types of Vacumnn Rotometer. Like this one in the picture to the right. Supplying Chlorine at a Wastewater Plant was an all-day and dangerous job.

Anywhere Chlorine Dioxide is measured out in precise increments, Chlorine Dioxide Generators are used to apply the chemical used with chlorine dioxide sensors which give a dissolved chlorine dioxide measurement in ppm or mg/l and their associated flow cells are available with different chlorine dioxide controllers giving you the same great performance with different communication, display, and control options.

  • Chlorine Dioxide Dosing Control
  • Remote Sites 
  • Cooling Towers
  • Food Preparation
  • Hospitals
  • Food & Drink Industry
  • Paper Mills
  • Hotel Industries
  • Airline and Cruise Ship Industry

Potable Aqua Chlorine Dioxide Tablets


Chlorine dioxide is one of a number of disinfectants that are effective against Giardia Lamblia and Cryptosporidium cysts, which cause diseases such as cryptosporidiosis in public drinking water supplies. A number of public waterworks are now utilizing chlorine dioxide generation systems alongside UV systems in order to provide complete protection from Cryptosporidium.

Chlorine dioxide is considered an oxidant. This means that chlorine dioxide removes electrons from another compound during a chemical reaction. This activity makes it toxic to many bacteria and fungi. Chlorine dioxide treated-water significantly reduced Escherichia coli (E. coli) bacteria, counts which is a big problem in polluted water from sources of wastewater.




Chlorine dioxide is considered potentially toxic to humans at concentrations higher than 0.8 mg/L. according to EPA Water purification tablets containing chlorine dioxide are marketed to outdoor enthusiasts like campers, hikers, and backpackers to help sanitize fresh water from rivers or lakes make sure to carefully follow the instructions on the package if you use these products, you need to never use more than the recommended quantity per volume of water to treat. Like Chlorine,  Chlorine is a chemical that can be harmful if not used right.






Disinfectant Fogging Solution


In hospitals, clinics, and other healthcare environments, chlorine dioxide gas helps to sterilize safe and effective medical and laboratory equipment, surfaces, rooms, and tools. Researchers have found that at appropriate concentrations, chlorine dioxide is both at helping to eliminate Legionella bacteria in hospitals and medical environments.

Chemical fogging: Applying chemical disinfectants to production areas as fogs or mists is a method used routinely in the food industry. The reason is to create and disperse a disinfectant aerosol to reduce the number of airborne micro-organisms and also to apply disinfectant to the many unseen and out-of-reach surfaces that may be difficult to get to. Fogging is achieved using either a static, purpose-built system in a factory area with strategically placed nozzles or, more commonly, a mobile unit that can do rooms individually.

Exposed room surfaces, such as ceilings, walls, floors, and equipment, while others may include some penetration into equipment to contact indirectly exposed surfaces. They may also provide disinfection of the air in the area being treated and breathed in during the workday.

Chlorine dioxide Disinfectant Fogger: using ClO2 gas is considered environmentally friendly as it rapidly breaks down into innocuous sodium salts. It is unstable and therefore is generated at its site of use by various chemical and electrochemical methods. It has been shown to be effective at 2mg L-1 and at >65% relative humidity for 12hrs. Mobile and fixed ClO2 generator systems that allow the automation of the application are commercially available.


Uses of Chlorine Dioxide


  • Disinfection in sewage water disinfection, industrial process water treatment, cooling tower water disinfection, industrial air treatment, mussel control, foodstuffs production and treatment, industrial waste oxidation, and gas sterilization of medical equipment.
  • Chlorine dioxide disinfectant is a gas with strong oxidizing properties that quickly neutralizes and eliminates odors.
  • Chlorine dioxide in both liquid and gas, which are often used in tandem for cases of extreme odors in all kinds of Industries
  • Chlorine dioxide eliminates foul odors caused by mold, mildew, smoke, and other organic sources. It can be used to remove Inorganic components, for example, manganese and iron, that can be used to remove bad tastes and odors and to reduce chlorine related disinfection byproducts.
  •  It can be used in Cooling and stripping towers used to treat Industrial Waste
  • It can be used at very low concentrations in the Food Processing Industry on can be used on fruits, vegetables, meats, and seafood for decontamination purposes
  • Irrigation disinfection purposes for greenhouses and large farms where Chlorine Dioxide is used in minimal amounts to sterilize crops.
  • There are Claims of Chlorine Dioxide can help fight diseases like Malaria the COVID -19 Virus


The only real reason and importance of Chlorine Dioxide are it’s disinfecting qualities in preventing dangerous drinking water from poisoning the population that suffers from Water Scarcity around the world. With a filter that comes in this bundle that is perfect for preparedness from natural events that may come.

  • Bundle Includes 1 Gravity Filter System (OB-25NF) AND Aquamira Chlorine Dioxide Drops for added disinfection
  • Removes Viruses, Bacteria, and Cysts, Including E. Coli and Giardia
  • Outback Produces 6-12 Gallons Per Day and Filters 1,800 Gallons before filter change / Aquamira drops treat 60 gallons when treating unknown water source
  • Perfect for Emergency or Disaster Preparedness: Portable. No Electricity. No Pumping. Simple Setup
  • Proven Record: For 25+ Years Outback Used by Disaster Relief Organizations

Outback Gravity-Fed Survival Water Filter System for Portable Emergency Filtration Bundled with Aquamira Chlorine Dioxide Pretreatment Drops-Removes Viruses & Bacteria 99.99% (Ships Free)



Chlorine Dioxide has unique effectiveness in the world of Disinfection and Sterizalation where Chlorine was once the only chemical that was used in Water Treatment practices. Which is an important process all around the world.

Water Scarcity and Drinking water are such huge problems and are in some countries the leading causes of death.  Disinfection of shallow Wells where villages can’t find clean drinking water or have the methods and equipment to clean it themselves smaller equipment and fewer chemicals.

According to the United Nations: Water scarcity, poor water quality, and inadequate sanitation negatively impact food security, livelihood choices, and educational opportunities for poor families across the world. At the current time, more than 2 billion people are living with the risk of reduced access to freshwater resources and by 2050, at least one in four people is likely to live in a country affected by chronic or recurring shortages of freshwater. Drought in specific afflicts some of the world’s poorest countries, worsening hunger, and malnutrition. Fortunately, there has been great progress made in the past decade regarding drinking sources and sanitation, whereby over 90% of the world’s population now has access to improved sources of drinking water.

Disinfection practices are a big part of that progress and success. Chlorine Dioxide Generators could be another way of keeping Water safe throughout the world Without the struggle we’ve had even up until the last decade.


According to the FDA, Chlorine dioxide products have not been shown to be safe and effective for any use, including COVID-19, but these products continue to be sold as a remedy for treating autism, cancer, HIV/AIDS, hepatitis, flu, among other conditions, despite their possible harmful effects.


How to Lower Free Chlorine


 JimGalloway Author/Editor





Cleaning and Disinfection: Whole room fogging-Dr. Karen E. Middleton, Technical Contracts Manager, Food Hygiene Department- k.middleton@campden.co.uk www.campden.co.uk

EPADrinking Water RegulationsDrinking Water Requirements for States and Public Water Systems

Sodium Chlorite Chlorine Dioxide Generators

The National Library of Medicine

5 Interesting Uses of Chlorine Dioxide + Safety, Side Effects Written by Puya Yazdi, MD | Last updated: 

Section HikerChemical Water Purification-Chlorine Dioxide Tablets



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