The pipes that serve individual hydrants and blocks of consumers are called __________, and can be installed into a grid system to reinforce them during times of high demand.

The correct term for the pipes that serve individual hydrants and connect to blocks of consumers is "distributors." These distributors are essential components of a firefighting water supply system, as they are specifically designed to deliver water to hydrants that are strategically located throughout an area.

In a comprehensive water supply system for firefighting, distributors can be organized in a grid system, which enhances their reliability and performance during periods of high demand, such as during a fire incident. This grid arrangement allows for multiple water supply pathways, ensuring that if one section of the system becomes compromised or demands increase, other routes can still deliver the necessary supply.

Choosing "distributors" highlights the system's design intent and operational capacity to maintain effective water pressure and availability, which is critical in emergency situations. The other terms, while related to water distribution systems, refer to different types or functions of pipes and do not accurately describe the specific role of these pipes in serving hydrants directly.