Exposed pipe or joint
Note the exact fitting, whether the water is constant and whether a nearby fixture changes it.
Leaks can show at a pipe or fitting, or travel before becoming visible. The first useful step is to record the visible location, nearby fixtures and when the water changes.

Note the exact fitting, whether the water is constant and whether a nearby fixture changes it.
Record the tap, toilet, basin, bath or shower and what was being used when the water appeared.
Describe the first damp patch, the rooms nearby and whether it is growing. Avoid opening walls or ceilings.
A contained leak can be described here. If water is spreading quickly, near electrics or coming through a ceiling, first read the urgent plumbing guidance or the ceiling-water guidance.
Add what was in use, whether water is still appearing and any safe photos that show both detail and wider context.
A clear message helps a plumbing professional understand the next step.