Under the Ground Water Rule (GWR), what type of sampling is mandated for larger systems regarding chlorine residual?

Continuous sampling under the Ground Water Rule (GWR) mandates that larger water systems monitor chlorine residual consistently to ensure the safety and quality of drinking water. This type of sampling provides real-time data on chlorine levels, allowing for immediate corrections to maintain safe residuals. The continuous monitoring system ensures that any fluctuations in residual levels are detected promptly, facilitating timely responses to potential contamination events or operational issues.

Regular checks throughout the distribution system help in maintaining compliance with safety standards, thus protecting public health. In contrast, the other methods of sampling do not provide the same level of ongoing data or immediate oversight that continuous sampling does. This ongoing monitoring is particularly crucial for larger systems where the risk of contamination can vary across different segments of the system.