08/09/2022 | Industrial Water Treatment | 9 MINUTE READ

Chlorine Dioxide Safe Use and Benefits in Water Treatment

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There are many different solutions that you can use to treat water and remove contaminants within, which include everything from ultrafiltration and reverse osmosis to chemical disinfectants. Among the most effective disinfectants is chlorine dioxide, which has long been a popular solution for water treatment.

Chlorine dioxide is a type of chemical compound that’s comprised of a single chlorine atom as well as two oxygen atoms. When at room temperature, chlorine dioxide is a yellowish-green or reddish gas that can dissolve in water.

The many uses of chlorine dioxide include disinfecting drinking water, antimicrobial uses, commercial water treatment, medical applications, paper manufacturing, and food/beverage production. This article offer a detailed look at if chlorine dioxide is safe to use and what benefits it can have when it comes to water treatment.

safe water

Uses & Benefits

There are a wide range of ways in which chlorine dioxide can be used. Despite chlorine dioxide being a chemical compound that poses some issues when consumed at high amounts, it’s also a potent disinfectant that can remove certain contaminants that other treatment methods are unable to get rid of.

Chlorine is known to be used in every facet of water treatment, which includes industrial and recreational applications. Along with disinfecting drinking water, chlorine is also able to disinfect swimming pools and cooling towers.

Chlorine Dioxide as a Disinfectant

Chlorine dioxide is regularly used as a disinfectant throughout many applications and is the preferred choice in numerous scenarios. Systems that contain biofilms and surface germs can benefit the most from chlorine dioxide as a disinfectant. This chemical is able to get rid of biofilms and effectively inactivate germs by completely destroying cell walls.

The disinfection and oxidation capabilities that chlorine dioxide have are 100% independent from the water’s pH levels, which means that you can use chlorine to disinfect water even if it has pH levels of 5.0 or 9.0. Chlorine dioxide is able to properly disinfect water as a result of the oxidation process. The chemical compound consists of 19 distinct electrons and will only react with other substances that can give off one of their own electrons. Chlorine will then substitute a chlorine atom with the other substance.

The organic substances that are found in bacterial cells are known to react directly with chlorine dioxide, which results in certain cellular processes being interrupted. In fact, protein production is effectively prevented in this scenario. Once bacteria are properly eliminated, the chlorine dioxide will get into the cell wall to keep these issues at bay.

To eliminate viruses in the water, chlorine dioxide will react with a water-soluble substance known as peptone. In this situation, protein formation is prevented, which leads to the virus dying. Because of how chlorine dioxide work, it’s considered to be a more effective disinfectant for viruses and bacteria than ozone or chlorine.

Chlorine dioxide is also among the only disinfectants that have proven to be effective when used to eliminate Cryptosporidium and Giardia Lambia parasites, which are sometimes present in drinking water. When consumed, these parasites can lead to serious diseases. Many water treatment facilities will combine chlorine dioxide with ozone to make sure that all parasites in the water are eradicated.

Another notable advantage of using chlorine dioxide as a disinfectant is that it reacts directly with the cell wall, which means that the reaction doesn’t depend on contaminant concentration or reaction time. Even when a microorganism is inactive, chlorine dioxide can eliminate it. Because of this process, it’s impossible for a microorganism to develop a resistance against this chemical compound, which is why many consider it to be more effective than other water treatment solutions.

chlorine dioxide as a disinfectant

As mentioned previously, chlorine dioxide is able to be used against biofilm since the chemical compound can penetrate into the slime layers of various bacteria. Chlorine dioxide will then oxidize what’s known as the polysaccharide matrix, which is what keeps the biofilm together. This process causes the chlorine dioxide to be reduced into chlorite ions.

In the event that the biofilm begins to grow, the chlorite ions introduce an acid environment that causes the ions to form into chlorine dioxide that will repeat the process. Because of this chemical reaction, chlorine dioxide is among the more effective solutions for getting rid of biofilm.

When looking specifically at drinking water treatment, chlorine dioxide was initially used to get rid of inorganic components like iron and manganese. Any odors or tastes in the water could also be removed. It’s possible for chlorine dioxide to operate as an oxidizing agent as well as a disinfectant.

If chlorine dioxide is placed into the water before oxidation, the growth of bacteria and algae can be prevented. Any floating particles in the water will be oxidized, which improves coagulation and helps to remove any turbidity from the water. Many drinking water plants use chlorine dioxide to eliminate viruses and bacteria since chlorine dioxide can be active for 48 hours or more.

Food and Beverage Production

Even though chlorine dioxide is mainly used for water treatment purposes, it has several additional applications, one of which involves food and beverage production. When food or beverages are being produced, chlorine dioxide serves as a type of antimicrobial agent within the water, which is why this water is regularly used during poultry processing as well as to wash vegetables and fruit.

Paper Processing

Chlorine dioxide is a highly important chemical during paper processing. In this situation, chlorine dioxide can be used to process wood pulp, which involves cooking wood chips in chlorine dioxide solutions at elevated pressures and temperatures.

Medical Applications

Chlorine dioxide has several medical applications that it can be used for. As a gas in hospitals and similar healthcare environments, chlorine dioxide is able to sterilize lab and medical equipment alongside rooms, tools, and surfaces.

At the right levels, chlorine dioxide is effective at getting rid of the harmful Legionella bacteria, which can lead to the deadly Legionnaires’ disease. Keep in mind that chlorine dioxide isn’t considered to be a treatment or cure that can be administered for medical ailments.

Safety Information

Even though chlorine dioxide is regularly used to effectively disinfect drinking water, it must still be handled properly to ensure that no one becomes sick or injured. In its natural gaseous form, chlorine dioxide is hazardous, which is why it’s highly recommended that you wear respiratory protective equipment when handling chlorine gas.

This equipment must contain 30 minutes of compressed air. Every operator in the water treatment facility should wear rubber gloves, goggles, and a protective apron. An eye washing station should also be available in the vicinity. Even though chlorine dioxide is a hazardous gas, the majority of people won’t breathe in too much chlorine dioxide since it breaks down quickly when introduced to air.

The U.S. Occupation Safety and Hazard Administration (OSHA) regulates chlorine dioxide use in workplace air for anyone who’s tasked with using this chemical compound. This administration has created a Permissible Exposure Limit (PEL) of 0.1 parts per million for all workers who use chlorine dioxide in industrial applications.

Keep in mind that chlorine dioxide gas must always be made at the industrial location where it’s meant to be used. The EPA has set guidelines to make sure that chlorine dioxide and other byproducts don’t have high concentrations in drinking water.

chlorine dioxide safety


It’s common for people to have concerns about consuming high amounts of chlorine dioxide since it’s a chemical compound. Along with being hazardous at high levels, chlorine dioxide can also be somewhat corrosive when left in a source of water for an extended period of time.

How Is Chlorine Dioxide Used in Water Treatment?

Chlorine dioxide is primarily used in water treatment as a disinfectant, an oxidant, and a biocide. This chemical compound can perform all of these tasks at low concentrations. It doesn’t create much byproducts when compared to other solutions.

When introduced to water at the right concentrations, chlorine dioxide is able to eliminate viruses, bacteria, and additional microbes to prevent waterborne diseases. If the chemical compound remains at a gaseous solution, it’s much more soluble than chlorine and can be properly removed via aeration.

Is Chlorine Dioxide Corrosive?

If you use chlorine dioxide at a concentration that allows the chemical compound to disinfect water, it will only be slightly corrosive. As mentioned previously, chlorine dioxide is much more soluble when compared to chlorine, which reduces the corrosive effects of the chemical.

Does Chlorine Dioxide Remove Odor?

When introduced to water, chlorine dioxide should remove bad odors and tastes from water. It can also kill the bacteria and algae that produce these odors/tastes in the first place. Because of its potency, chlorine dioxide is commonly used in personal hygiene, dentistry, and mouthwash products.

Is ClO2 Toxic and Can It Be Stored Safely?

You can’t store chlorine dioxide as a gas since a risk of explosion occurs when concentrations become higher than 10%. If you store chlorine dioxide for a lengthy period of time, it will break down into the chlorite byproduct before eventually turning into chlorate. The chemical only separates into oxygen and chlorine when it’s in a gas phase.

When storing this chemical, it should be stored at concentrations of 0.3% ClO2. Make sure that the solution is kept far away from heat or light sources. If chlorine dioxide is stored in good conditions, it should remain soluble and stable.

Chlorine dioxide is among the most effective solutions for eliminating viruses, pathogens, and bacteria from water, which is why the majority of water treatment facilities and industrial plants use chlorine dioxide as a disinfectant. Since chlorine dioxide is hazardous as a gas, it must be handled properly before and while you’re using it.

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Posted by Dominic O'Donnell on August 9, 2022

Sensorex is a global leader in the design and manufacture of quality sensors for water quality and process applications. The company offers more than 2000 sensor packages for pH, ORP, conductivity, dissolved oxygen, free chlorine, chlorine dioxide, UV transmittance and other specialty measurements, as well as a full line of sensor accessories and transmitters. Its expert technical support engineers solve analytical sensor challenges with custom designs and off the shelf products.

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