No Hot Water? What to Check First
A short, safe checklist for gas, electric and tankless water heaters, and the signs that it is time to stop troubleshooting and call a plumber.
Updated November 12, 2026 · By the Water Heater Repair Raleigh team
If you have no hot water, first check whether other hot taps are cold too. For an electric heater, check the breaker and the high-limit reset button. For a gas heater, check that the gas is on and whether the pilot or burner is lit. For tankless, note the error code. If the breaker trips again, the pilot won't stay lit, or you smell gas, stop and call a plumber.
Step 1: Is it the whole house?
Run hot water at a sink and a shower. If only one fixture is cold, the problem may be that fixture's mixing valve, not the heater. If every tap is cold or lukewarm, keep going.
Electric water heaters
- Breaker: find the water heater breaker (usually a double-pole breaker) and check whether it has tripped. Reset it once. If it trips again, leave it off. That points to an element or wiring fault.
- High-limit reset: many electric heaters have a red reset button behind the upper access panel. It trips when the water gets too hot. Pressing it is a common homeowner step, but turn off the breaker first and follow the manufacturer's instructions. If it keeps tripping, a thermostat or element has likely failed.
- Lukewarm water that runs out fast often means the lower element or thermostat has failed.
Gas water heaters
- Gas supply: check that other gas appliances work and the valve on the heater's gas line is open.
- Pilot or burner: older tanks have a standing pilot you can see through a small window. Newer ones use an electronic igniter and may flash a status light. Relight only by following the instructions on the heater's label.
- Pilot won't stay lit: a common sign of a failing thermocouple or flame sensor, or a gas control valve problem.
- Smell gas: don't relight anything. Leave and call the gas company or 911 from outside.
Tankless water heaters
- Check that the unit has power. Gas tankless units still need electricity.
- Write down the error code and look it up in the owner's manual.
- Try one fixture at a time. Very low flow may not trigger the unit to fire.
- See tankless water heater help for common causes.
When to stop and call a plumber
- The breaker or reset button trips again.
- The pilot won't light or won't stay lit.
- You see water around the heater (see leaking water heater).
- You smell gas or see scorch marks near the burner.
- The heater is old and this keeps happening (see repair or replace).
Frequently asked questions
Why do I have no hot water but the pilot is on?
The burner may not be firing because of the gas control valve or thermostat, or the thermocouple may not be holding the gas valve open. A plumber can test each part.
Why is there no hot water after a power outage?
An electric heater may have tripped its breaker or high-limit reset. A gas heater with electronic ignition may need to restart. Check the breaker and the heater's status light.
Is no hot water an emergency?
Usually it's urgent rather than dangerous. It becomes an emergency if you smell gas, see water leaking near electrical parts, or the relief valve keeps discharging.
How long should it take for hot water to come back?
A tank heater needs time to reheat a full tank after it has been off. If there's still no hot water well after that, something has failed.
Related help
No hot water or a leaking tank?
Turn off the power or gas to the heater and close the cold-water valve above it if water is leaking. Then get help from an independent local plumber.