What should you do first when a water heater is leaking?
Shut off the water supply to the heater and switch off its power or gas. Move people and items away from the water, and call the line. A leaking heater is a flood risk and an electrical or gas risk at the same time, so the first steps are about safety and the water supply.
Find the cold-water shutoff for the heater, which is usually on the supply pipe above it, and turn it off clockwise until it stops. Turn off the breaker for an electric heater, or the gas control for a gas heater, and leave it off until a qualified person has checked it.
Do not try to repair the tank yourself or tighten a fitting that is dripping under pressure. A leak from the body of the tank cannot be fixed by tightening, and the attempt can make the leak worse.
Why does a water heater leak cause damage beyond the floor?
Water from a heater can reach the floor, the bottom of the walls, the cabinet bases and any stored items close by. It can also reach the subfloor below the heater, which is hidden from view. The crew reads all of those routes, not only the visible pool.
A tank holds a large volume of water, and a steady leak can soak a floor overnight. The water runs under cabinets and along baseboards before it stops. The crew measures the spread of the wet area with the readings, so the drying covers the whole route.
Hot water can also loosen floor coverings and warp wood trim, and that damage can show some days later. The crew checks those materials on each return visit, so any later change is recorded.
Can the water heater be repaired or does it have to be replaced?
A leak from a fitting may be repairable, while a leak from the tank body usually means replacement. A qualified person decides which applies after the heater has been drained and checked. The crew does not decide this alone, and it tells the homeowner what the check found.
The age of the heater, the location of the leak and the condition of the other parts all affect the decision. A heater that has leaked from the body should not be patched and used again, because the leak will return.
The homeowner should ask for the check result in writing, because it decides whether the heater can be used and what must be replaced. Keep that note with the drying record and the receipts.
What gas and electrical checks are needed after a heater leak?
A gas heater needs its controls, venting and gas connections checked before it is used again, and an electric heater needs its wiring and breaker checked. Water that reached the controls can cause a fault that is not visible from outside. A qualified person does the check, and the crew keeps the heater off until it is done.
Electrical items near the heater, such as the outlet, the breaker panel and the switch, are checked for moisture before power is restored to the area. The electrical safety guidance on this site explains that check in more detail.
Gas appliances need a qualified person's check before they are lit again. Do not relight a gas heater yourself after a leak, even if it appears to be working.
How do you keep a water heater leak from causing damage next time?
A drain pan under the heater, a drain line to a safe outlet and a shutoff valve that is easy to reach all reduce the damage from a future leak. A heater that is checked regularly is less likely to fail without warning. The crew can explain the options, and a qualified person can advise on the equipment.
Keep the area around the heater clear of stored items, so that a leak is seen sooner and the water has less to soak. Check the drain pan and the drain line occasionally for water.
Consider a water sensor on the floor near the heater, which can alert you early. A sensor is not a substitute for a check, but it can shorten the time before a leak is found.
