Water Heater Not Working? 9 Fixes to Try (2026)
Water Heater Not Working? 9 Fixes to Try (2026)
Aire One East Heating & Cooling, 1910 Dundas St E #117, Whitby
A water heater not working means a cold shower and a scramble to fix it, but the cause is often something simple and safe to check yourself first. This guide walks through the checks to try, the faults that need a technician, and the gas and electrical safety rules that always come first. If the checks do not restore hot water, see our water heater repair page.
- First confirm cold water flows normally, so you know a water heater not working is the unit and not the supply.
- On an electric unit, a tripped breaker or a tripped reset button is the most common cause of a water heater not working.
- On a gas unit, an out pilot light or a closed gas valve is the usual culprit.
- Water pooling around the base means a leak, which is urgent and usually needs replacement, not a DIY fix.
- If you smell gas, leave the house first and call the gas utility from outside; never troubleshoot a gas smell.
Short answer: when your water heater is not working, confirm cold water runs, check the thermostat setting, reset the breaker or the red reset button on electric units, and relight or check the gas on gas units, before calling.
If those do not restore hot water, or you see a leak or smell gas, call a licensed technician. Aire One East runs 24/7 across Durham Region. Call 905-576-7600.
Water heater not working: the checks to try first
Most of the time, a water heater not working comes down to a few simple things, and these are safe to check yourself. Run through them in order before you book a service call, and know whether you have a gas or electric unit first.
- Confirm it is the water heater: run a cold tap. If cold water flows fine but hot does not, the problem is very likely the water heater itself.
- Check the thermostat setting: the dial should be around 49 degrees Celsius; if it was turned down, turn it up and wait an hour or two.
- Electric unit, check the breaker: reset a tripped breaker labelled for the water heater, and wait for the tank to reheat.
- Electric unit, press the reset button: a red high-limit reset button behind an upper panel trips on overheating; press it once.
- Gas unit, check the pilot and valve: confirm the gas valve is on, and if the pilot light is out on an older unit, relight it following the label instructions.
If none of these restores hot water and a water heater not working continues, the cause of the water heater not working is likely internal and needs a licensed technician.
Why is there no hot water?
When the free checks do not solve a water heater not working, one of these faults is usually the reason. A few you can handle; the rest need a professional.
| Fault | Unit type | Who fixes it |
|---|---|---|
| Tripped breaker or blown fuse | Electric | You once; a pro if it trips again |
| Tripped reset (high-limit) button | Electric | You once; a pro if it trips again |
| Failed heating element | Electric | Pro |
| Pilot light out or closed gas valve | Gas | You, or the gas utility |
| Faulty thermocouple or igniter | Gas | Pro |
| Thermostat set too low or faulty | Both | You to set; a pro if faulty |
| Sediment buildup in the tank | Both | Pro, flush or replace |
| Leaking tank | Both | Pro, urgent, usually replace |
Ranked by how often they cause a no-hot-water call, verified August 2026.
Why is my water lukewarm or running out fast?
Not every water heater not working is a total no-hot-water case. Lukewarm water or hot water that runs out quickly usually points to a partly failed component rather than a dead unit. On an electric heater, a burned-out lower heating element leaves you with warm but never hot water, or a short supply. On any unit, heavy sediment buildup insulates the water from the heat source, so the tank heats slowly and empties fast. A thermostat set too low is the simplest cause. Turn the temperature up first; if the water is still lukewarm, an element or thermostat likely needs replacing by a technician.
Water heater not working: when to call a pro
Some signs mean stop and call rather than keep trying. A water heater not working after the free checks, water pooling around the base, a breaker or reset that trips again, rusty or foul-smelling hot water, rumbling or popping noises, or any gas smell all point to professional work. Our TSSA-licensed team covers Whitby, Oshawa, Ajax, Pickering, Courtice, Bowmanville, Port Perry, and Uxbridge with 24/7 emergency service, and a maintenance and protection plan keeps your system ahead of most failures. A leaking tank in particular is urgent, because it rarely stops on its own and can cause water damage.
Key terms in this article
- Heating element: the electric component that heats the water; upper and lower elements can burn out and leave you with little or no hot water.
- Reset button: a red high-limit switch on electric units that trips when the water overheats and can be pressed once to reset.
- Thermocouple: a gas-unit safety part that confirms the pilot flame; when faulty, the burner will not stay lit.
- Sediment buildup: mineral deposits at the bottom of the tank that slow heating and cause rumbling.
- Pressure relief valve: a safety valve that releases excess pressure; a leaking or stuck one needs immediate attention.
Frequently asked questions
| Your water heater questions, answered |
|---|
| Why is my water heater not working all of a sudden? A water heater not working suddenly is most often a tripped breaker or reset button on electric units, or an out pilot light or closed gas valve on gas units. Confirm cold water still flows, then check those; they solve many no-hot-water calls without a service visit. |
| How do I reset my water heater? On an electric unit, first reset the breaker labelled for the water heater, then press the red high-limit reset button behind the upper access panel once. If it trips again, stop and call a technician, because a repeated trip signals a fault. |
| Why do I have lukewarm water but not hot? Lukewarm water usually means a partly failed heating element on an electric unit, heavy sediment slowing the heat transfer, or a thermostat set too low. Turn the temperature up first; if it stays lukewarm, an element or thermostat likely needs a technician. |
| Is a leaking water heater an emergency? Water pooling around the base is urgent. A tank leak rarely stops on its own and can cause water damage, and it usually means replacement. Shut off the water supply to the tank and call for service; do not try to seal a leaking tank. |
| Can I fix a water heater not working myself? You can safely confirm cold water flows, adjust the thermostat, reset the breaker or reset button, and check a gas valve. Anything involving heating elements, the burner, the thermocouple, or a leak requires a licensed technician, and any gas smell means leave and call the gas utility. |
Do not take our word for it alone. Read our 364 verified reviews on Google, and see the Heating, Refrigeration and Air Conditioning Institute of Canada for what accredited contractors are expected to deliver.
