Where are disinfection by-products samples collected from?

Disinfection by-products (DBPs) are formed when disinfectants used in water treatment, such as chlorine, react with organic matter present in the water. For accurate monitoring and regulation of these substances, sampling typically occurs within the distribution system. This approach is crucial because it allows operators to assess the levels of DBPs after water has been treated and delivered through pipes, but before it reaches the end user.

Sampling from the distribution system provides a better representation of what consumers will experience in their tap water. It takes into account any changes in water quality that may occur due to long retention times in the distribution network or reactions that might happen in different sections of the system.

While source water and points of use are important for other assessments, they do not provide the same level of insight into DBP levels as sampling from the distribution system. Source water may contain different organic materials that could lead to a different DBP profile, and sampling at customer taps may also reflect additional variables introduced after water leaves the distribution system. Therefore, focusing on the distribution system is essential for ensuring compliance with health regulations and effectively managing water quality for consumers.