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

What common chemical is used for disinfecting small water supplies?

1. Calcium carbonate

2. Calcium hypochlorite

3. Chlorine dioxide

4. Bromine

The correct answer is: Calcium hypochlorite

Calcium hypochlorite is a widely used disinfectant for small water supplies due to its effectiveness in killing bacteria, viruses, and other pathogens. It is a solid compound that can be easily transported and stored, making it particularly practical for small water systems. When dissolved in water, it releases chlorine, which acts as a powerful oxidizing agent, providing a strong disinfection capability. This compound is particularly valued for its stability and solubility; it can be used in different forms, including granules and tablets, providing flexibility in application methods. Moreover, calcium hypochlorite is often favored for its ability to provide residual disinfection in water systems, meaning it continues to protect water after initial treatment, which is crucial for maintaining water quality in distribution systems. While other disinfectants like chlorine dioxide and bromine have specific applications, they might not be as universally used for small water supplies as calcium hypochlorite. Chlorine dioxide, for instance, is effective but requires more careful handling and monitoring due to its unique properties and potential for by-product formation. Bromine is generally used in specific circumstances, such as in hot tubs or pools, rather than conventional small water supply systems. Calcium carbonate, on the other hand, is primarily utilized for