Which step should follow the initial chlorine breakthrough measurement?

After the initial chlorine breakthrough measurement, pausing treatment is an important and necessary step. This action is typically taken to prevent the potential negative effects of chlorine levels that exceed safe operating parameters. Excessive chlorine can lead to harmful reactions, including the formation of disinfection byproducts, which could compromise water quality and safety.

By halting the treatment process, staff can assess the situation more thoroughly and determine the cause of the breakthrough. It provides an opportunity to evaluate whether the system is operating correctly and whether adjustments are needed to ensure that water meets safety standards. This pause allows for necessary adjustments and precautions to be taken before resuming treatment, ultimately protecting both the water supply and the health of consumers.

The other options may be part of the overall response to a chlorine breakthrough, but the immediate priority is to ensure that the treatment does not continue until it is deemed safe to do so.