What is the most common disinfectant used in the water industry?

Free chlorine is the most common disinfectant used in the water industry due to its effectiveness in killing a wide range of pathogens, including bacteria, viruses, and protozoa. It is favored for its residual disinfection capability, which means that it remains in the water after treatment and continues to provide protection against pathogens as the water travels through the distribution system. This residual effect is crucial for maintaining water quality and ensuring safety for end-users.

Additionally, free chlorine is cost-effective, easy to monitor, and can be applied in various forms, such as gas, liquid, or solid, making it versatile for different treatment scenarios. Its ability to form chlorinated compounds that can further inhibit microbial growth also contributes to its widespread use in municipal water systems. Given these advantages, free chlorine remains the primary choice for disinfecting drinking water in many regions around the world.