When water is actively going where it should not, the first goal is not diagnosing the perfect repair. It is reducing additional damage without putting yourself in danger.
Start with safety
If water is near electrical equipment, outlets, wiring, a damaged ceiling, or another obvious hazard, keep your distance and get qualified emergency help. Do not enter standing water when electrical hazards may be present.
Stop the water if you can do so safely
For a fixture or appliance, an accessible local shutoff may stop the flow. If you cannot identify the source or local shutoff, the home’s main water shutoff may be appropriate. Know where it is before an emergency and do not force a valve that is damaged, inaccessible, or unfamiliar.
Protect what you can
Move belongings away from the affected area when it is safe. Use containers or towels for minor controlled water, but do not place yourself beneath a bulging or damaged ceiling or attempt cleanup in an unsafe area.
Take photos
Document the visible source, affected rooms, damaged materials, and belongings before cleanup when doing so will not delay necessary emergency action. If an insurance claim may be involved, contact your insurer for instructions about documentation and mitigation.
Figure out who owns the next step
A leaking supply line, fixture, drain, water heater, roof, appliance, HVAC component, or buried pipe may require different professionals. If the source is unclear, explain what you can observe rather than guessing at the diagnosis.
Do not confuse stopped water with a solved problem
Turning off the supply can stop additional water, but wet building materials may still require drying, inspection, or repair. Hidden moisture can matter even after the visible puddle is gone.
For future reference: photograph your main water shutoff now and save a trusted plumber’s contact information before you need either one.
General educational information only. Water and electricity can create serious hazards. For unsafe conditions, major flooding, structural damage, sewage, or uncertain electrical risk, leave the affected area and use qualified emergency professionals.