When is sodium thiosulfate most commonly used in water treatment?

Sodium thiosulfate is most commonly used in water treatment specifically for its ability to neutralize chlorine residual. Chlorine is frequently used as a disinfectant in water treatment processes, but it can be necessary to remove any excess chlorine before water enters distribution systems or is dispensed for consumption. Sodium thiosulfate reacts with chlorine to form non-toxic byproducts, effectively reducing the chlorine levels in the water and preventing any potential adverse effects associated with its residual presence.

This application is critical not only for protecting drinking water quality but also for ensuring that sensitive aquatic life is not harmed by chlorine in effluent discharged into natural water bodies. The use of sodium thiosulfate in this context highlights its importance in maintaining both human health and environmental safety.