A chlorinator should have the capacity to provide at least how much free chlorine residual?

The correct choice for the capacity of a chlorinator to provide at least 2 mg/l of free chlorine residual aligns with established public health and safety standards for water disinfection. A free chlorine residual of this level is essential for ensuring that pathogens are effectively inactivated in drinking water. It provides a sufficient buffer against potential contamination that could occur after the initial treatment phase, maintaining water quality as it moves through distribution systems to consumers.

Free chlorine serves not only to disinfect water but also acts as a residual agent to protect water quality from recontamination. Levels below 2 mg/l may not offer a robust defense, particularly in systems where recontamination risks exist. This level is particularly significant in situations where there may be increased demands on chlorine, such as higher levels of organic material or bacterial contamination in the water supply.

Selecting a residual of 2 mg/l balances effective disinfectant properties while not being excessively high, which could lead to taste and odor issues or chlorination byproducts that may pose health risks. Thus, maintaining this minimum residual level is a critical practice for ensuring safe and reliable drinking water.