Fire Water Supply

What does a jockey pump actually do in a fire-pump system?

The jockey pump is a small pressure-maintenance pump that tops the system pressure back up after a tiny leak or thermal drift, so the main fire pump does not short-cycle every time pressure dips. It runs on small drops; the main pump only starts on a real demand like an open sprinkler.

Related questions

• When is a diesel fire pump required instead of an electric one?
• Why does a building need a fire department connection if it already has a city water supply?