Overskuddsklor

Overskuddsklor is a term used in Norwegian environmental management literature to denote the condition in which chlorine maintained in a water treatment system exceeds the target residual level, resulting in a surplus of reactive chlorine species in the distribution network. The word combines overskudd (surplus) and klor (chlorine).

In practice, overskuddsklor may arise from over-dosing chlorine, delayed degradation of residuals, or measurement biases, and it is typically distinguished from the intentional, controlled dosing of disinfectant.

Applications and interpretation: In municipal water utilities, overskuddsklor is monitored to prevent distribution system corrosion, taste and odor issues, and formation of disinfection byproducts. Tracking overskuddsklor helps operators adjust dosing, trigger dechlorination steps, or optimize contact times.

Management and mitigation: When overskuddsklor is detected, operators may reduce chlorine dosing, use dechlorinating agents like sodium bisulfite, or adjust pH to influence chlorine speciation. Regular calibration of sensors and routine water quality testing are used to prevent sustained overskuddsklor.

Regulatory and health considerations: Excess chlorine can cause irritation and the formation of byproducts such as trihalomethanes; however, the term overskuddsklor is primarily a process-control issue, not a separate contaminant. Standards for residual chlorine are set by local authorities, and overskuddsklor events are typically logged and reviewed for process improvement.

See also: chlorine residual, water treatment, disinfection byproducts, dechlorination.