Where must positive bacti resampling take place?

The requirement for positive bacterial sampling, or "bacti", resampling is based on ensuring that the water supply is safe and not contaminated beyond the original detection. When a positive result for coliform bacteria is obtained, it's critical to conduct resampling not only at the original location where contamination was first detected but also at one point upstream and one point downstream.

Sampling in these three locations helps to assess the extent of contamination within the water distribution system. By sampling downstream, operators can determine if the contamination has spread beyond the original location. Sampling upstream is equally important because it helps identify whether the source of the contamination might be coming from an issue further back in the system. This comprehensive approach provides a clearer picture of water quality and helps in taking necessary corrective actions if needed.

Consequently, resampling at these specified locations is a crucial step in effective water quality monitoring and management, as it helps ensure the safety of the water supply for consumers.