Which of the following can be a primary source of TTHMs?

The presence of TTHMs (Total Trihalomethanes) in drinking water is primarily linked to the use of chlorine-based disinfectants. When these disinfectants are used to treat drinking water, they can react with naturally occurring organic matter in the source water, such as decaying vegetation and other organic compounds. This reaction leads to the formation of TTHMs, which are considered a byproduct of the chlorination process.

Chlorination is a common and effective method for controlling microbial pathogens in water supply systems. However, it is essential to monitor and manage the formation of TTHMs because they are regulated contaminants due to their potential health risks, which can include long-term effects when consumed.

The incorrect options focus on other aspects of water quality and treatment. Organic compounds do play a role in the formation of TTHMs when reacted with chlorine; however, it is the chlorine-based disinfectant specifically that is the primary source for these compounds, not the organic matter itself. High water pressure systems and physical contaminants do not directly contribute to the formation of TTHMs and are therefore not relevant to the question of primary sources.