Define the term "drainage system" in a fire sprinkler context.

In the context of fire sprinkler systems, the term "drainage system" specifically refers to a system designed to remove water from the sprinkler system. This is crucial for several reasons, including the prevention of water accumulation that could lead to further damage or create hazards within the facility. The drainage system ensures that any residual water after a test or activation of the sprinklers can be evacuated effectively, maintaining the integrity of the fire protection system and preventing potential issues such as freezing in colder climates or corrosion.

The other options focus on different functionalities that are not related to drainage. While water distribution and flow monitoring are important aspects of the overall sprinkler system operation, they do not pertain directly to the function of draining water. Emergency water supply access is a vital component as well, but it relates more to ensuring water is available during a fire incident, rather than the removal of water from the system post-activation or testing. Thus, the definition of a drainage system in this context distinctly highlights its role in safely maintaining and managing water presence within the fire sprinkler system.