What factor usually triggers the need for additional treatment measures during water processing?

The presence of excessive organic material in the source water is a critical factor that often necessitates additional treatment measures during water processing. Organic materials can originate from a variety of sources, including agricultural runoff, sewage discharge, and natural events like flooding. When organic material concentrations are high, it can lead to a range of water quality issues, including an increased risk of microbial growth, elevated biochemical oxygen demand (BOD), and the formation of disinfection byproducts when chlorine is used for disinfection.

When water treatment plants encounter high levels of organic material, they may need to implement advanced treatment techniques such as enhanced coagulation, activated carbon filtration, or biological treatment processes to effectively remove these materials. In contrast, other factors mentioned, such as high temperatures, increased pH levels, and low turbidity, might not trigger a similar level of concern concerning the need for immediate additional treatment, as they don't inherently indicate a significant risk to water quality the way excessive organic material does.