How is disinfection byproducts compliance calculated?

Disinfection byproducts compliance is calculated using a locational running annual average because this method provides a comprehensive assessment of water quality over time. The locational running annual average (LRAA) takes into account the concentrations of disinfection byproducts measured at specific sampling locations over the preceding 12 months. This allows water systems to assess trends and fluctuations in disinfection byproduct levels, ensuring they remain within regulatory limits.

Using the LRAA is crucial because it provides a more representative measure of customer exposure to these compounds than a single sample or an average over a shorter time period. The LRAA helps to account for variability in water quality caused by factors such as seasonal changes, variations in water source, and treatment processes.

In contrast, other methods, like calculating compliance based on average concentration over short periods or just the highest concentration detected, might not accurately reflect the ongoing exposure levels, potentially leading to either underestimations or overestimations of compliance with regulations. This makes the locational running annual average a key approach for ensuring safe drinking water standards are met consistently over time.