If cold water lines are contaminated, to what level should the free chlorine be raised during hyper-chlorination?

Hyper-chlorination is a method used to disinfect water systems, particularly when there is a concern about contamination in cold water lines. The appropriate level of free chlorine is critical to effectively kill pathogens while also considering the safety and palatability of the water.

In the context of hyper-chlorination for contaminated cold water lines, raising the free chlorine concentration to a level between 20 and 50 mg/L is typically effective for disinfection purposes. This concentration is sufficiently high to eliminate bacteria, viruses, and protozoa that may be present in the water without causing excessive risks to human health.

Levels within this range ensure that the chlorine is effective in penetrating biofilms and reaching harmful microorganisms, promoting a thorough disinfection process. Additionally, while levels above this range might further enhance disinfection, they could lead to taste and odor issues in the water or may pose risks when consumed. Thus, maintaining the balance between efficacy and safety is important, making the range of 20 to 50 mg/L the ideal choice for hyper-chlorination of contaminated cold water systems.