CR-37 Plumbing Practice Test 2026 – Complete Exam Prep

The requirement for the concentration of chlorine in a water main repair solution is typically set to ensure effective disinfection of the water system. A concentration of 200 parts per million (ppm) is widely accepted as an adequate level to eliminate harmful bacteria and pathogens that could compromise water quality during a repair process.

When conducting repairs, the intention is to disinfect the newly installed or repaired sections of the water main, and using chlorine at this concentration is effective in achieving that goal without causing harm to the pipes or adversely affecting water quality. Higher concentrations, while possibly effective, may be unnecessary and could lead to complications such as corrosion or excessive chlorine taste and odor. Therefore, using 200 ppm strikes a balance between effectiveness in disinfection and safety for both the infrastructure and the end-users.