4 min read · Updated August 22, 2026
Damage in a water event is a function of volume, and volume is a function of time. Everything below is ordered by what reduces that first.
1. Stop the water
Closest valve first, main second.
- A fixture is overflowing or spraying: close the angle stop underneath it. Toilets and sinks have one; turn it clockwise.
- A supply line has burst, or you cannot identify the source: go to the main and close it.
- A water heater is leaking: close the cold-water shutoff above the unit, then shut off its power or gas.
If you do not know where your main is, that is worth solving today rather than during an emergency.
2. Deal with electricity before you deal with water
If water is contacting outlets, light fixtures, appliances or an electrical panel, do not enter the water. Shut off power to that area at the breaker if you can reach the panel safely and it is dry. If you cannot, stay out and call an electrician or the fire department.
This is the point where a plumbing emergency becomes a life-safety situation, and it is the step people skip.
3. Know which situations are not plumbing calls
- Suspected gas leak: leave the building. Do not use switches, phones or anything that sparks inside. Call the gas utility from outside.
- Sewage in living space: this is a biological hazard. Keep people, pets and food preparation out until it has been cleaned and disinfected properly.
- Ceiling sagging or bulging with water: stay out from under it. That is a structural collapse risk, not just a stain.
4. Limit the damage
Once the water is off and the area is safe: move what you can, get standing water up, and open the space to air. Photograph everything before you move it — insurers ask, and memory is not evidence.
5. Then call
For an urgent situation, call rather than filling in a form. Have ready: what happened, what you already shut off, whether the water is stopped now, the property address, and whether anyone else is affected — a unit below, a neighbouring tenant, a business next door.
For property managers
The version of this that belongs in your resident handbook is short: where the unit shutoff is, what to do first, who to call, and what qualifies as an emergency. Residents who know where their shutoff is cost you dramatically less than residents who do not.
This article is general information about how plumbing systems behave. It is not a diagnosis of your building, and it is not instructions for performing regulated work. Gas, electrical, pressurised systems, sewage contamination and code-regulated work belong with the appropriate licensed trade.