Which of the following is NOT a common well disinfectant?

Sodium bicarbonate is not a common disinfectant used for wells. It is primarily known for its role as a buffering agent and for modifying pH levels in various applications. In the context of water treatment and well disinfection, the focus is generally on substances that can effectively kill bacteria, viruses, and other pathogens to ensure the safety of drinking water.

Chlorine is widely used due to its effectiveness in disinfection processes. It can efficiently eliminate a broad range of microorganisms. Potassium permanganate is also utilized, primarily for its oxidizing properties, which can help in the treatment of certain types of contaminated water systems and pathogens. Fluoride, while more associated with dental health and preventing tooth decay, is typically not classified as a disinfectant.

Thus, sodium bicarbonate stands out as the correct answer, as its primary functions do not include disinfection, making it less relevant in discussions about common well disinfectants compared to the other substances listed.