What is the recommended chlorine target when disinfecting a new pipeline with calcium hypochlorite tablets or granules?

The recommended chlorine target when disinfecting a new pipeline with calcium hypochlorite tablets or granules is 25 mg/L. This concentration is established to ensure effective disinfection while being safe for the materials typically used in water distribution systems.

At 25 mg/L, the chlorine concentration is sufficient to eliminate harmful microorganisms and pathogens that can thrive in new pipe systems. This level also allows for adequate contact time to ensure thorough disinfection throughout the entire pipeline. It's essential to strike a balance between effectiveness and potential corrosion or damage to pipes and fittings; hence, the choice of 25 mg/L is crucial as it minimizes risks associated with higher chlorine levels while still achieving the required disinfection standards.

In contrast, higher concentrations such as 50 mg/L or 100 mg/L may pose risks of pipe damage or undesirable taste and odor in the water, while lower levels like 10 mg/L would be insufficient to meet the disinfection requirements.