Should You Turn Off Water Heater When Water Is Off?

Ever wondered what to do with your tankless water heater when the incoming water supply suddenly stops? It’s an emergency situation that leaves many homeowners puzzled. Should you leave the thermostat on or switch it off? Let’s dive into this predicament.

Leaving your tankless water heater on during a water outage can have consequences you might not expect. The absence of water can cause the thermostat to malfunction, potentially leading to damage or even a leak. However, turning off the breaker might result in complications when restoring the water supply for homeowners.

To make an informed decision about your water heater, homeowners should consider several factors, including the tankless feature, gas control, and the pilot light. Are you expecting a long outage? Is there a risk of freezing pipes? Evaluating these aspects will help determine whether shutting down your tankless water heater with gas control and a pilot light is necessary.

There isn’t a one-size-fits-all answer when it comes to deciding whether to turn off your tankless water heater during a temporary loss of running H2O. Let’s explore the impact and factors involved, such as gas control, vacation, and repair.

should you turn off water heater when water is off
should you turn off water heater when water is off

How shutting off the main water supply affects your water heater

Potential risks of leaving your water heater connected to an inactive water supply

Going on vacation without shutting off the main water supply can lead to significant issues with your house’s water heater. It is crucial for residents to understand the potential risks of leaving their water heater connected to an inactive water supply, as it could require costly repairs.

  1. Loss of Water Pressure during Vacation: When residents go on vacation and turn off the main water supply to their house, there will be a loss of water pressure in the pipes connected to the home. This drop in pressure can impact the performance of the water heater, leading to inefficient heating or even damage. It’s important to note that plastic pipes are more susceptible to this issue.

  2. Dry Firing: If you continue using a water heater in your house without an active water supply, it can result in dry firing. Dry firing occurs when there are no adequate amount of water present in the tank, causing the heating elements or burners to overheat and potentially burn out. This can be a problem for home residents.

  3. Sediment Buildup: Without a flowing water source, sediment that accumulates at the bottom of your tank may not be flushed out properly. Over time, this heat-related sediment buildup can affect efficiency and lead to corrosion or other issues within the tank for Jackson residents.

  4. Safety Concerns for Jackson Residents: In case of emergencies like leaks or excessive heat, having an active main water supply allows for quick shut-off and prevents further damage or hazards. Without this immediate control, safety concerns for Jackson residents may arise.

During temporary loss of running water, it is crucial for Jackson residents to take precautions with their water heater by following these steps.

  1. Turn Off Power/Gas Supply: Before shutting down the main water supply, ensure that power (electricity) or gas supply is switched off for safety reasons.

  2. Drain Tank if Necessary: If you anticipate an extended period without running water, consider draining your tank partially or completely as per manufacturer’s instructions to avoid stagnant conditions and prevent any potential damages caused by sediment accumulation.

  3. Monitor Water Supply Restoration: Stay informed about updates regarding the restoration of the main water supply in your area. Once water is restored, take necessary steps to flush and refill your water heater before resuming regular usage.

By understanding how shutting off the main water supply affects your water heater and taking appropriate precautions during temporary water loss, you can ensure its optimal performance and longevity.

Steps to take when shutting off a gas water heater

  • Safely shutting off a gas-powered hot-water system is crucial to prevent damage or accidents.

  • Follow these simple steps to ensure proper shutdown procedures are followed for your traditional water heaters. Make sure to turn off the gas supply to your house water heater before proceeding. Start by locating the incoming water supply valve and turning it off. This will prevent any more hot water from entering the tank. Finally, turn off the gas supply valve to fully shut down the unit.

  • Before proceeding, make sure you understand how to safely relight your gas-powered hot-water system after restoring the main supply.

  1. Locate the gas control valve: Find the gas control valve on your water heater. It is usually located near the bottom of the unit.

  2. Turn off the gas supply: Rotate the valve handle clockwise until it is perpendicular to the pipe. This will shut off the flow of gas to the water heater.

  3. Turn off the pilot light: If your water heater has a pilot light, turn it off according to manufacturer instructions. Usually, this involves turning a knob or pressing a button labeled “pilot” and holding it down until the flame goes out.

  4. Close all hot-water faucets: To prevent any residual pressure from building up in your plumbing system, close all hot-water faucets throughout your house.

  5. Consider draining the tank: If you anticipate an extended period without water supply, you may choose to drain your water heater tank following manufacturer guidelines. This step can help prevent any potential damage caused by stagnant water sitting in the tank.

Remember, safety should always be a priority when dealing with gas appliances like water heaters. By following these steps and taking necessary precautions, you can ensure a smooth shutdown process for your gas-powered hot-water system and avoid any mishaps when restoring its operation later on.

Steps to take when shutting off an electric water heater

Familiarize yourself with essential steps for properly turning off an electrically powered hot-water system.

  1. Locate the breaker box: Before proceeding, identify the breaker that controls your electric water heater. It is typically labeled and can be found in the electrical panel of your home.

  2. Turn off the power supply: Once you’ve located the correct breaker, switch it to the “off” position. This will cut off electricity to your water heater, ensuring safety during a temporary loss of running water.

  3. Follow manufacturer guidelines: Different electric water heaters may have specific instructions for shutting down their systems. Refer to the user manual or contact the manufacturer for any additional steps or precautions.

Safely disconnect power sources and follow recommended guidelines for electric heaters during a temporary loss of running water.

  1. Shut off the cold-water supply valve: Locate and close the valve that supplies cold water to your electric water heater. This step prevents any potential damage or leaks while there is no running water.

  2. Drain excess water from faucets and pipes: Open several faucets in your home to drain any remaining water from the plumbing system. This helps prevent freezing or damage caused by stagnant water when there is no supply.

  3. Consider installing a bypass pipe: If you anticipate prolonged periods without running water, consult a professional about installing a bypass pipe that allows you to temporarily connect an alternative source of water directly to your hot-water system.

Be prepared to reestablish power and restore normal operation once the main supply is restored.

  1. Restore power after resumption of main supply: When running water returns, ensure all faucets are closed before switching on the breaker controlling your electric water heater in order to avoid dry-firing (heating without enough liquid).

  2. Allow time for heating: Electric heaters may take some time to reheat after being turned back on, so be patient while waiting for the water to reach the desired temperature.

Remember, safety should always be a priority when dealing with electrical appliances. If you have any doubts or concerns about turning off your electric water heater, it’s best to consult a professional plumber or electrician for guidance.

Reasons why plumbers recommend turning off water heaters during water outages

Preventing damage, leaks, and other issues

Turning off your hot-water system during a plumbing emergency is a precautionary measure that professional plumbers often advise. By doing so, you can prevent potential damage, leaks, and other issues that may arise due to inactivity and pressure changes.

  • Inactivity: When the water supply is cut off, leaving the water heater on can cause it to continue heating an empty tank. This can lead to overheating and potentially damage the heating elements.

  • Pressure changes: Water outages can result in fluctuating pressure levels once the supply is restored. If your hot-water system remains on during this time, the sudden increase in pressure could cause leaks or bursts in pipes and fittings.

Cost savings through reduced energy consumption

Another benefit of turning off your water heater during a plumbing emergency is the potential cost savings. By reducing energy consumption while waiting for regular access to running tapwater, you can save money on utility bills.

  • Energy reduction: Hot-water systems continuously heat the water stored in their tanks. When there’s no water supply, this constant heating becomes unnecessary and wasteful.

  • Utility bill savings: By temporarily shutting off your water heater during a plumbing emergency, you can avoid unnecessary energy usage and reduce your overall utility costs.

Understanding the potential risks of not turning off your water heater during a water outage

Leaving your water heater on during a water outage can lead to various consequences that you should be aware of. Neglecting to turn off your hot-water system can result in significant risks, including damage, leaks, and even explosions. It is crucial to consider the potential financial implications and safety hazards associated with keeping your water heater on when there is no water supply.

Recognize possible consequences that may arise from leaving your water heater on during a water outage. These include:

  • Water damage: Without any incoming water supply, the continuous operation of your water heater can cause leakage or flooding if there are existing issues with the tank or pipes.

  • Pressure build-up: When there is no flow of cold water into the tank, pressure can build up inside it. This increased pressure may lead to bursts or other malfunctions within the system.

  • Explosions: In extreme cases, pressure build-up combined with malfunctioning safety valves can result in catastrophic explosions, causing severe damage to property and endangering lives.

Understand the risks of damage, leaks, or even explosions that can occur due to pressure build-up or other factors. It is essential to take precautions and turn off your water heater during a water outage to mitigate these risks effectively.

Consider the potential financial implications and safety hazards associated with neglecting to turn off your hot-water system. By being proactive and switching off your water heater when there is no access to running water, you can avoid costly repairs, prevent property damage from leaks or floods, and ensure the safety of yourself and others.


It’s important to make a smart decision when it comes to your water heater during a water outage. Turning off your water heater can affect it, whether it’s gas or electric. Plumbers recommend turning off water heaters during water outages for a few reasons. To protect your water heater, it’s important to understand the risks of not turning it off during a water outage. You should follow specific steps for shutting off gas and electric water heaters. When deciding whether to turn off your water heater, think about its safety and how long it will last. While it may be inconvenient to temporarily disable it, taking precautions can prevent expensive repairs or damage from unexpected events. To be prepared for future water outages, talk to a professional plumber. They can give you advice on how to properly shut down your water heater and answer any questions you have. Remember, maintaining your water heater is important for its performance and lifespan. By being proactive and informed about turning it off during a water outage, you can avoid problems and make it last longer.


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