Florida Drinking Water Operator "B" Practice Test

Which type of bacteria is most commonly targeted by chlorine disinfection?

1. Coliform bacteria

2. Spores

3. Viruses

4. Fungi

The correct answer is: Coliform bacteria

Chlorine disinfection primarily targets coliform bacteria because these microorganisms are often used as indicators of water contamination and the effectiveness of the disinfection process. Coliform bacteria, particularly Escherichia coli (E. coli), are present in the intestines of warm-blooded animals, and their presence in water signals possible fecal contamination, which could indicate a risk of waterborne pathogens. The use of chlorine is effective in reducing the levels of coliform bacteria in water systems, thus improving safety for human consumption. While chlorine can also affect other microorganisms, including some viruses and bacteria spores, the emphasis on coliform gives water operators a clear and practical focus on managing water quality and ensuring public health safety.