Which of the following is NOT one of the three rules that require monitoring water within the distribution system?

The correct answer identifies the Nitrate Rule as the one that does not require monitoring water within the distribution system.

The Trihalomethane Rule, Lead and Copper Rule, and Total Coliform Rule are all critical regulations that focus on monitoring water quality in distribution systems to ensure public health and safety.

The Trihalomethane Rule addresses the presence of byproducts that can form when chlorine is used for disinfection, requiring utilities to monitor these levels within the system to protect consumers from potential adverse health effects.

The Lead and Copper Rule focuses on the monitoring of lead and copper levels in drinking water to minimize the risks associated with plumbing materials that can leach these metals into the water supply.

The Total Coliform Rule mandates routine monitoring for coliform bacteria in the distribution system, as these can be indicators of harmful pathogens' presence.

The Nitrate Rule, while important, primarily governs the levels of nitrates in raw water sources and does not specifically mandate ongoing monitoring within the distribution system itself, making it distinct from the other three rules regarding distribution system requirements.