Ontario Operator-in-Training (OIT) Practice Exam

What is the significance of monitoring residual chlorine levels in treated water?

1. To ensure taste quality

2. To determine the effectiveness of disinfection

3. To control water temperature

4. To measure water pressure

The correct answer is: To determine the effectiveness of disinfection

Monitoring residual chlorine levels in treated water is crucial for determining the effectiveness of the disinfection process. Chlorine is commonly used as a disinfectant because it effectively kills harmful bacteria, viruses, and other pathogens that can be present in water. The presence of residual chlorine indicates that the disinfectant is still active in the water, which suggests that disinfection has occurred successfully. If residual chlorine levels are sufficiently high, it confirms that the initial chlorine dose was adequate and that the water treatment process was effective. Additionally, the monitoring of these levels helps to ensure that the water supply remains safe for consumption as it continues to be distributed through the system. If residual chlorine were to be absent or low, it could indicate that the water might not have been adequately disinfected, posing health risks to consumers. While aspects like taste quality, water temperature, and water pressure are important in the overall management of drinking water systems, they do not provide information about the effectiveness of the disinfection process in the way that monitoring residual chlorine does.