Texas Commission on Environmental Quality (TCEQ). Class C Water License Exam

Which of these is a challenge in maintaining water quality?

1. Keeping temperature constant

2. Controlling groundwater levels

3. Preventing chlorine residual decay

4. Minimizing water flow rates

The correct answer is: Preventing chlorine residual decay

Preventing chlorine residual decay is a significant challenge in maintaining water quality in distribution systems. Chlorine is commonly used as a disinfectant in water treatment processes to ensure that harmful microorganisms are killed and that the water remains safe for consumption. However, chlorine can decay or dissipate over time as water travels through the distribution system, especially if the water is exposed to higher temperatures, organic materials, or light. Maintaining an adequate chlorine residual is crucial because it helps to prevent the regrowth of bacteria and protects against contamination as water moves to consumers. If chlorine levels drop below acceptable thresholds, it poses a risk to public health. The other considerations, while they may impact water quality indirectly, do not directly address the specific challenge of maintaining disinfection levels in treated water. Keeping temperature constant and controlling groundwater levels pertain more to broader environmental management issues, and minimizing water flow rates could be related to different operational strategies but do not specifically address the preservation of chlorine residuals in the system.