What is the typical percentage of sodium hypochlorite in water distribution systems?

The typical concentration of sodium hypochlorite used in water distribution systems is indeed around 5.25%. This concentration is effective for disinfection purposes, as sodium hypochlorite is a powerful oxidizing agent and serves as a chlorine source for chlorination in the treatment of drinking water. The 5.25% solution is commonly used because it provides a balance between effectiveness and manageability for treatment facilities, enabling adequate dosing while minimizing risks associated with handling and storage. The concentration allows for a sufficient residual chlorine level in the water, ensuring that pathogenic microorganisms are effectively inactivated during the treatment process.

Higher concentrations, like 7.0% or 10.0%, may be available but are less common for water treatment due to increased safety risks, more complicated handling procedures, and potential for higher corrosive effects on treatment facilities and distribution systems. In contrast, a lower concentration of 3.5% may not provide adequate disinfecting power, particularly in larger water systems where stronger doses are necessary to maintain safe water quality standards.