Upon receiving a positive bacteriological sample from a testing point, what should the operator do next?

Upon receiving a positive bacteriological sample from a testing point, the operator should collect another sample at the site as well as one upstream and downstream. This approach is essential for several reasons.

First, obtaining an additional sample at the original test site allows the operator to confirm or refute the initial result. Inconsistent results may indicate a temporary issue or an error with the sample collection or analysis process.

Collecting upstream and downstream samples is equally crucial as it helps determine if the contamination is localized to the testing point or if it may be part of a larger issue affecting a broader area of the water system. This comprehensive sampling strategy provides critical information on the potential source and extent of contamination.

Taking this step ensures that the water supply's safety can be accurately assessed and that appropriate measures can be taken to protect public health, such as notifying the appropriate authorities or implementing remedial actions if necessary.