The guideline for neutralizing residual halogen with sodium thiosulfate in potable water is found in which CIM?

• A. CIM 6240.5
• B. CIM 5216.4
• C. CIM 6000.1
• D. CIM 5100.5

Answer: (A)

The main idea here is where the formal procedure for neutralizing residual halogen in potable water lives. When water is disinfected with chlorine, a residual amount remains that can interfere with tests or damage personnel handling the water. Neutralizing that residual halogen with sodium thiosulfate is a standard step to make sampling and analysis safe and accurate. The CIM that contains the exact guidelines for potable water disinfection practices, including how to neutralize residual halogen with sodium thiosulfate, is the one designated for potable water management and disinfection procedures. That’s why this option is the best choice.

The other CIMs cover topics outside potable water disinfection guidance, so they do not contain the specific neutralization instructions for residual halogen in potable water.