What concentration of chlorine is necessary to disinfect a distribution line or tank?

To effectively disinfect a distribution line or tank, a chlorine concentration of 50 ppm is generally recommended. This optimal concentration is effective in eliminating various pathogens, including bacteria and viruses, which can be present in water systems, ensuring that the water delivered to consumers is safe for use.

A level of 50 ppm strikes a balance between providing adequate disinfection while minimizing the risk of residual chlorine levels that could affect water taste or potentially react with organic materials, leading to the formation of disinfection byproducts. It is a concentration that can penetrate biofilms and ensure thorough disinfection throughout the distribution system.

Higher concentrations, such as 100 ppm or 200 ppm, might provide additional disinfection but are often unnecessary for typical applications and can lead to problems such as more taste and odor issues or increased toxicity to aquatic life if the water is released into the environment. On the other hand, a lower concentration, such as 10 ppm, may not be sufficient to ensure effective disinfection, especially in systems with heavier contamination. The choice of 50 ppm is therefore based on achieving effective microbial control while considering practical application issues in water treatment processes.