When a routine water sample tests positive for total coliform, what is one of the required steps?

When a routine water sample tests positive for total coliform, one of the critical steps is to collect a repeat sample from the same tap and from locations both upstream and downstream of that tap. This approach is essential because it helps to determine whether the contamination is localized to a specific point or if it affects a broader section of the water distribution system. By sampling upstream, you can assess if there is a source of contamination prior to the tap, while sampling downstream can show if the contamination propagates through the system.

This method aids in pinning down the potential causes of contamination and is part of a comprehensive response strategy required by water quality regulations. The repeat sampling can help operators make informed decisions regarding necessary corrective actions, ensuring the safety and integrity of the drinking water supply.