Power outages can affect home hot water systems differently depending on whether the unit is electric or gas. This guide explains when you need to relight, how to safely restart, and what steps to take to prevent issues after an outage. Understanding these points helps ensure reliable hot water while avoiding safety hazards.

Key takeaways: Electric water heaters often require nothing more than resetting the thermostat or circuit breaker after a brief outage. Gas-fired units may need a manual pilot relight or ignition reset, and always follow the manufacturer’s instructions. If you smell gas, or if the water heater won’t relight, seek professional assistance.

How Power Outages Affect Water Heaters

Electric water heaters rely on an electric heating element and thermostat. A power outage may cut power to the unit, and when power returns, a reset or re-arming of the thermostat might be required. In most cases, there is no pilot light to relight, and the heater will resume heating once the circuit is restored and the thermostat is set correctly.

Gas-fired storage water heaters use a standing pilot light or an electronic ignition. A power interruption can affect the electronic components and may temporarily disable the ignition system. If the pilot is already lit, the outage might not require relighting, but the system may need a reset to reestablish proper operation. In some models, a minimum power supply is required for the electronic ignition to function, so the unit may not relight until power is restored.

Hot water tanks rely on a combination of temperature controls and safety devices such as a thermocouple or flame sensor. After an outage, these sensors may need to be re-synced or tested to ensure reliable ignition and safe operation. Always follow the manufacturer’s guidance when dealing with these components.

Relighting a Gas Water Heater With a Pilot Light

For gas-fired units with a standing pilot light, relighting should be safe if performed carefully and following the manufacturer’s instructions. If the unit uses a newer electronic ignition, skip to the section on electric relighting below.

First, ensure ventilation and check for gas odors. If you smell gas, evacuate and call the gas company or emergency services.
Turn the gas control knob to the “Off” position and wait at least five minutes to clear any gas buildup.
Set the control knob to “Pilot” and press and hold the reset button (or hold the knob in the pilot position, depending on the model) to allow gas to flow to the pilot.
Light the pilot with a long, match-safe lighter or built-in igniter while continuing to hold the control knob in the pilot position for about a minute.
Release the knob after the pilot stays lit. If the flame goes out, repeat the process or consult a professional.
Turn the control knob to the “On” position and set the thermostat to your desired temperature, typically around 120°F (49°C).

Safety note: If you cannot relight the pilot after multiple attempts, or if the flame is yellow or irregular, shut off the gas and contact a licensed plumber or gas technician. Faulty ignition or damaged thermocouples pose safety risks.

Relighting an Electric Water Heater After a Power Outage

Electric water heaters generally do not have a standing pilot. After a power outage, the main action is to restore power and reset thermostats as needed. Follow these steps:

Confirm the circuit breaker or fuse for the water heater location is ON. If you reset a tripped breaker, wait a few minutes for the unit to regain power.
If the water taking longer to heat suggests temperature loss, wait for the heater to recover its setpoint. Most electric heaters have a high-temperature limit switch that may trip during a surge; if tripped, this safety cutout may require a manual reset behind an access panel.
Check the thermostat settings. If the water is not reaching the expected temperature, you may need to re-set the thermostat. Setpoints commonly range from 120°F (49°C) to 140°F (60°C), with 120°F being a safe standard for most homes.
Allow sufficient time for the tank to recover. A 30–60 minute window is typical for many 40-50 gallon units, depending on recovery rate and incoming water temperature.

Tip: If your electric water heater has a thermostat lockout or advanced control, refer to the user manual for the exact reset procedure, as models vary by make and year.

Safety Considerations After a Power Outage

Power outages can create additional concerns beyond ignition. Sediment buildup can impact efficiency, and a temporary lack of power may affect safety devices that monitor temperature and pressure. After power returns:

Inspect for any water leaks around the tank and connections.
Test the pressure relief valve if you know how to do so safely, following the manufacturer’s guidelines. Do not test without understanding the procedure, as this can be dangerous.
Check for unusual noises, odors, or dampness, which may indicate a problem with the tank or wiring.
Consider replacing or upgrading older units. Energy-efficient models with advanced controls may be more reliable after outages and offer better fault detection.

Routine maintenance, including flushing the tank annually and checking anode rods every 2–3 years, can improve resiliency and extend the life of the water heater, reducing future outage-related issues.

When To Call a Professional

Relighting a gas water heater is straightforward for many homeowners, but certain situations require professional help:

Gas smell persists after attempting ignition, or if the pilot won’t stay lit.
The unit does not heat water after power is restored, or the thermostat does not respond.
There is visible damage, leaks, or signs of water damage around the unit.
Electrical components show burn marks, a buzzing sound, or frequent breaker trips during power restoration.
You’re unsure about safety or the correct sequence for your specific model.

Professional service can verify venting, gas pressure, ignition reliability, and electrical safety, preventing potential hazards.

Practical Quick-Reference Checklist

Identify your water heater type: electric or gas with standing pilot or ignition.
Check for gas smells; if present, do not attempt relighting and call professionals.
For electric heaters, restore power and reset thermostats if needed.
For gas pilots, follow manufacturer-specific relighting steps or contact a licensed technician.
Inspect safety devices, leaks, and noise after power restoration.

Following these steps helps ensure a safe and reliable hot water supply after a power outage while reducing the risk of injury or equipment damage.

Important note: Always consult the user manual for your specific model and consider professional help if you are uncertain about any part of the process or safety concerns arise.