Bleach vs Gas Chlorination: Choosing the Best Method for Water Disinfection Treatment

When it comes to ensuring safe and clean water, wastewater and water treatment plants have multiple options. Leading these options today, are gas and bleach chlorination. With multiple options, it is important to truly understand the pros and cons of each option.  

Difference Between Gas and Bleach Chlorination 

Chlorination is the process of adding chlorine to drinking water to kill parasites, bacteria, and viruses. The two most common chlorination treatments today are gas and bleach. Gas chlorination involves using chlorine gas (Cl2) to disinfect water. This method has been in use for over a century to treat water. Chlorine gas is typically stored in cylinders and fed into the water treatment system by a vacuum-operated system which is mounted directly on to the chlorine cylinder valve. Sodium hypochlorite (NaOCl) known as liquid bleach, is produced by injecting liquified chlorine gas into a reaction chamber filled with sodium hydroxide. The bleach is then stored in a tank and metered into the water 

Effectiveness of Chlorination Methods 

Gas Chlorination is a highly effective disinfectant, capable of eliminating many pathogens. It provides a more consistent and powerful chlorine residual in the water, ensuring thorough disinfection. Chlorine gas does not introduce additional chemicals into the water, as it simply dissolves to form hydrochloric acid (HCL) and hypochlorous acid (HOCl), which is also a powerful disinfectant. 

Bleach Chlorination is a useful method, with sodium hypochlorite being the active ingredient, attacks proteins in target cells which inactivate bacteria, viruses, and fungi. However, bleach disinfection has its limitations since it can be easily inactivated by organic material and loses activity quickly in its presence. In addition, Sodium Hypochlorite solutions can also degrade over time, especially with heat and sunlight exposure which can reduce their disinfection power. 

Safety Comparison 

Chlorine gas is one of the safest water disinfection methods used today. While Other chlorination methods have experienced significant accidents regularly, Chlorine gas rarely poses an issue. Improper chemical mixing has repeatedly caused large chlorine gas releases from sodium hypochlorite facilities without chlorine gas containers onsiteAlso, media reports often fail to mention causes other than chlorine containers. Sodium hypochlorite generation facilities have had numerous explosions, due to unvented Hydrogen gas, narrowly avoiding loss of life by sheer luck,” says Howard Specker, President, Superior Water Solutions.  

Superior Gas chlorinators are designed to have a vacuum regulator with an inlet valve which controls the pressure of the chlorine flow and acts as the safety shut-off valve in the event that a vacuum line is broken or removed; therefore, gas does not leak into the air.  

In comparison statistics show that bleach is the form of chlorine most involved in accidents and injuries. With numerous accidents and hospitalization occurring when other chemicals are accidentally mixed with the bleach to liberate chorine gas into the operating area. Handling of bleach containers also creates splashing hazards with eye damage and skin irritations, as well as corrosion of equipment and ruined clothing. 

Price comparison 

When comparing the price of these common water disinfection methods, gas chlorination trends towards being a more cost-effective option than bleach. The pricing of gas chlorine varies based on the supplier, however the average cost per pound of gas chlorine is $0.45. The price of bleach is estimated to be $1.43 per pound. Therefore, gas chlorine is a more cost-effective option for treatment plants 


In conclusion, both Gas and Bleach chlorination have their place in water and wastewater treatment plants. However, when comparing the two on a deeper level, gas chlorination is a more effective and safer treatment method. Utilizing gas chlorination also provides a higher level of safety and is more cost effective when compared to bleach chlorination. Learn more about our gas chlorinators here. 

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