Why is pretreatment with chlorine being eliminated in many water treatment plants?

• A. It is ineffective at disinfection
• B. It can produce carcinogenic by-products
• C. It causes water to taste bad
• D. It is more expensive than alternatives

Answer: (B)

The elimination of pretreatment with chlorine in many water treatment plants is primarily due to its potential to produce carcinogenic by-products, such as trihalomethanes (THMs) and haloacetic acids (HAAs). When chlorine reacts with organic matter present in the water, these harmful by-products can form. The presence of such compounds poses significant health risks to consumers, leading to increased regulatory scrutiny and public concern.

As a result, many water treatment plants are seeking alternative disinfection methods or pre-treatment processes that minimize or eliminate chlorine use to ensure safer drinking water and comply with health standards. This shift reflects a growing understanding of the need for more effective strategies that not only disinfect the water but also avoid the formation of hazardous substances.