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A few checks are safe for any homeowner, such as confirming that the breaker hasn't tripped, relighting a pilot by following the instructions printed on the heater's label, or noting exactly where water is coming from. Anything beyond that involves household voltage, gas or a tank under pressure, and belongs with a licensed professional.
The key question is whether the heater can be fixed at all. Elements, thermostats, valves and gas controls can be replaced; a tank that leaks through its own wall can't, and the conversation turns to a new unit.
Water heater problems by symptom: what they usually mean
- No hot water from an electric tank: a tripped breaker, a high-limit safety switch that has cut the power, or a failed element or thermostat.
- No hot water from a gas tank: the pilot has gone out or won't stay lit, the igniter has failed, or the gas supply to the heater is off.
- Hot water runs out fast: on an electric tank, the lower element has often failed and left only the upper one heating, while on any tank a thick layer of sediment takes up room.
- Water that is only lukewarm: a thermostat set too low or misreading, a broken dip tube letting cold water mix in at the top, or a burner that isn't firing properly.
- Discoloured hot water while the cold runs clear: the heater is the likely source, and a plumber can tell whether the anode rod or the tank itself is corroding.
- A rotten-egg smell in the hot water only: usually bacteria in the tank reacting with the anode, which is quite different from a gas smell in the air around a gas heater.
- Popping, rumbling or hissing: sediment on the tank bottom or on the elements, or water dripping onto a hot burner.
Safe checks before calling for water heater repair
None of these checks involves opening access panels, removing covers or touching wiring or gas fittings. Stop as soon as something looks wrong, and call a professional.
- Electric heater: look for a tripped breaker on the water heater's circuit; if it trips again after being reset, leave it off and call for service.
- Gas heater: look through the viewing window for the pilot flame or the burner, and make sure the gas control isn't set to its pilot or vacation position.
- If the pilot is out, relight it only by following the lighting instructions on the label attached to the heater, and don't try at all if you smell gas.
- Many newer gas and tankless models show a status light or an error code; note it before you call, since it helps the technician bring the right part.
- Look at the relief valve's discharge pipe: a steady drip or a flow of hot water means the temperature, the pressure or the valve needs a plumber's attention.
- Never plug, cap or remove a dripping relief valve, since it is the safety device that keeps the tank from building dangerous pressure.
- Write down the model and serial number from the label so the technician can check parts before the visit.
Water heater leaks: when a repair works and when the tank needs replacing
Finding where the water comes from is the first job. Wipe the area dry and look again a little later. Water at the hot or cold connections on top, around the drain valve at the bottom, at an element gasket on an electric model or from the relief valve's discharge pipe can usually be stopped by tightening or replacing that part. Condensation on a cold tank, or dripping from a gas burner when it first fires, can also look like a leak and fades once the water is hot.
Water seeping from the tank body, from under the insulation jacket or with rust weeping around the base is another matter: the inner tank has corroded through, and no repair will hold. Shut off the cold water supply to the heater, switch off its breaker or set the gas control to off as the label shows, and arrange a replacement before the leak gets worse. On an older heater, it's also worth asking whether an expensive part such as a gas control valve is worth putting into it; the water heater installation page covers choosing the next unit.
Gas and electrical safety around a water heater
Natural gas and propane are given a rotten-egg smell. If you smell it, Technical Safety BC advises leaving the area immediately and calling your gas utility, propane supplier or 911; don't flip switches or try to relight anything on the way out. Carbon monoxide has no smell at all, and Health Canada notes that it can only be detected with a CO alarm. If an alarm sounds, leave the home immediately, call 911 or your local fire department, and go back in only after a professional has fixed the problem.
Natural Resources Canada lists soot stains around a combustion appliance and melted plastic fittings at the top of a water heater among the signs that combustion gases may be spilling into the house, and advises calling an experienced professional to inspect it. Health Canada recommends having fuel-burning appliances inspected by a professional at least once a year, or as the manufacturer specifies. Repairs on the gas side belong to an authorized gas contractor, such as a CMMTQ member in Quebec or a TSSA-registered fuels contractor in Ontario, and an electric heater's elements and thermostats sit behind covers that only a qualified technician should remove, with the power off.
Electric, gas and tankless water heater repairs: what differs
- Electric tank: most repairs involve an upper or lower heating element, its thermostat or the high-limit switch, all of which are replaceable parts.
- Gas tank with a standing pilot: a thermocouple or flame sensor that no longer detects the flame, a dirty pilot or a faulty gas control are the usual suspects.
- Power-vented gas tank: its fan needs electricity, so it stops during an outage, and a blocked vent or a failed pressure switch will shut it down.
- Tankless unit: scale in the heat exchanger, a clogged inlet filter, a flow sensor or an ignition fault, usually reported as a code on the display.
- Heat pump water heater: a dirty air filter, a blocked condensate drain or a room that has become too cold can cut its output.
Water heater problems that show up in a Canadian winter
- Hot water runs out sooner because the water arriving from the street is colder, so a heater that barely kept up in summer may fall short in January.
- A power-vented, direct-vent or condensing heater that shuts off after a storm may have snow or ice blocking its outdoor exhaust or intake.
- A condensing heater's condensate line can freeze where it runs through a cold space and shut the unit down.
- A heater in an unheated garage, crawl space or cottage can freeze and crack if left full, so have it drained or protected before the cold arrives.
Water Heater Repair: frequently asked questions
Why do I suddenly have no hot water?
On an electric heater, check for a tripped breaker first; if the breaker is fine or trips again, an element, a thermostat or the high-limit switch has probably failed. On a gas heater, look for the pilot or burner flame and check the gas control setting. If the pilot won't light or won't stay lit by following the label, call a gas technician.
Can I relight the pilot light on my water heater myself?
Yes, if you follow the lighting instructions on the heater's label step by step and there's no smell of gas. If the pilot goes out again, won't light, or burns weak and yellow, stop there: the thermocouple, the gas control or the venting needs a qualified gas technician.
Is it normal for the water heater's relief valve to drip?
A drip that keeps coming back or a flow of water from the discharge pipe isn't something to ignore. It can mean the water is overheating, the pressure in the plumbing is too high, or the valve itself is worn. Have a plumber find the cause, and never cap the pipe or remove the valve to stop the drip.
Why does my hot water smell like rotten eggs?
When the smell comes only from the hot taps, bacteria in the tank are usually reacting with the anode rod. A plumber can treat the tank or replace the anode with a different type. If instead you smell rotten eggs in the air near a gas heater, treat it as a possible gas leak: leave and call your gas utility or 911.
Can a leaking water heater be repaired?
It depends on where the water comes from. A leak at a pipe connection, the drain valve, an element gasket or the relief valve can usually be fixed. A leak from the tank itself, or rust seeping from under the jacket, means the tank has corroded through and has to be replaced.
Sources
Written by the LokalMatch editorial team. Reviewed by Zubair Afzal on September 10, 2026. How we write and check our guides