A pipe repair provider
For a damaged private supply line, describe the location, whether it is active and whether water can be isolated. Confirm availability and the assessment terms.
Your water utility
If water appears to come from street infrastructure, report it to the utility. Responsibility boundaries vary; ask the utility about the particular line rather than assuming the meter boundary is universal.
The property manager
In a rented or shared building, alert the person who can authorize access and work. Provide the unit, affected floor and any visible change in the leak.
Emergency services when there is immediate danger
If there is an immediate threat to people, leave the dangerous area and contact the appropriate emergency service. A repair booking does not replace an emergency response.