How does salt electrolysis Work?

What is salt electrolysis?

Salt electrolysis is an electrochemical process in which dissolved table salt (NaCl) is converted, using an electric current, into hypochlorite and hypochlorous acid (HOCl), the active substances that disinfect water. This principle is familiar from swimming pools, but in the process industry, the same concept is used to prevent biofilm formation and microbially induced corrosion (MIC) in piping systems.

How Does Salt Electrolysis Work? The Chemical Process

The process always follows the same basic steps, whether it’s for a swimming pool or an industrial process water system:

1. Salt dissolves in water to form a saturated salt solution
2. During electrolysis, an electric current passes through the water, allowing the salt to be converted into a disinfectant
3. In this process, the salt water is converted into hypochlorite and hypochlorous acid: the active disinfectants
4. Hydrogen gas and sodium hydroxide are produced as byproducts
5. The amount of disinfectant produced and the amount of electricity required depend on the type of device and its settings

In short: a salt electrolysis system is nothing more than a system that, powered by electricity, produces disinfectant on-site.

Watter System: Automatic Quality Control

Our Watter system uses the same principle of electrolysis of water and salt to produce HOCl: an effective disinfectant.

The system continuously monitors and regulates the process, ensuring that quality is automatically controlled. This allows for the on-site production of a stable disinfectant without the need for manual adjustments or the risk of over- or underdosing

Salt electrolysis in swimming pools versus in the process industry

Salt electrolysis is merely the basic method from which different substances, such as NaOCl and HOCl, can be formed:

For both industries, an almost identical process is used, but the active substance and the purpose of the application are significantly different.

Why Biofilm and Corrosion in Pipes Pose a Greater Risk Than Previously Thought

Biofilm is a layer of microorganisms that adheres to wet surfaces, such as the insides of pipes, heat exchangers, and cooling systems. Local oxygen differences develop beneath the biofilm: the covered area becomes oxygen-deprived and acts as an anode, while the surrounding metal remains oxygen-rich. This difference accelerates pitting corrosion (1). This microbially induced corrosion (MIC) is common in water pipes and industrial installations and can impact production. Research on copper corrosion in piping networks shows that biofilm formation can directly lead to leaks and malfunctions if it is not actively controlled (2, 3).

Controlling MIC in pipes begins with limiting biofilm formation on the surface; continuous dosing of HOCl is one of the common methods used for this purpose (3).

What matters in salt electrolysis in industry

Advantages (general):

• No supply and storage of hazardous chemicals required.
• Local on-demand production, directly aligned with current needs.
• Lower storage costs and less logistical dependence on suppliers.

Points of attention in industry:

• Purchasing and installing the Watter system requires an upfront investment, unlike simply buying chlorine.
• Electricity is required: HOCl is produced using power, so make sure you have a proper electrical connection.

With the Watter system in industry:

• The system is configured based on the volume of water flowing through it and the water quality, to ensure stable operation.
• Because a constantly low HOCl concentration is dosed, energy consumption remains low and the stress on materials is limited.

Salt Electrolysis: A Versatile Process

Salt electrolysis is, in fact, one specific application of a broader electrochemical principle: producing a disinfectant on-site from water, salt, and electricity. That same principle also underlies the systems Watter builds for the process industry: no supply of chemicals, but HOCl produced on-site and continuously dosed to control biofilm and corrosion in pipes. While the swimming pool sector uses it to ensure clear pool water, industry employs the exact same reaction to protect process water and piping networks.

References

1. NIH ORF – "Corrosion in Closed-Loop Water Systems, Part 1." https://orf.od.nih.gov/TechnicalResources/Documents/Technical%20Bulletins/25TB/Corrosion%20in%20Closed-Loop%20Water%20Systems%20Part%201%20-%20Understanding%20Corrosion%20-%20May%202025%20TB%20_508.pdf
2. Judit Knisz, et al. "Microbiologically Influenced Corrosion – More Than Just Microorganisms." FEMS Microbiology Reviews, vol. 47, no. 5, 12 juli 2023. https://academic.oup.com/femsre/article/47/5/fuad041/7223462
3. PMC – "The Microbiologically Influenced Corrosion and Protection of Pipeline Materials" (2024). https://pmc.ncbi.nlm.nih.gov/articles/PMC11509198/