Why is ozone not sufficient as a long-term disinfectant in distribution systems?

Ozone is a powerful oxidant and effective disinfectant that can kill a wide range of microorganisms. However, its inability to provide a persistent residual in the water distribution system is a significant limitation for its long-term use as a disinfectant. In water treatment processes, a disinfectant that leaves a residual is crucial because it helps to inhibit the regrowth of bacteria and other pathogens after treatment.

Once ozone is applied, it quickly decomposes back into oxygen, resulting in no lasting disinfectant effect in the distribution system. This lack of persistent residual means that, while ozone can effectively disinfect the water at the treatment facility, it does not continue to protect the water once it enters the distribution network. This opens the possibility for contaminant introduction and microbial regrowth, which poses health risks to consumers.

On the other hand, while considerations related to cost, toxicity, and potential staining issues are important, they are not the primary reason ozone is not suitable as a long-term disinfectant. The need for a disinfectant with a lasting residual is central to maintaining water quality throughout the entire distribution system, making it vital for ensuring continuous protection against pathogens.