Yes, you should usually turn off the water heater when the water supply is shut off, especially if the tank may become empty during plumbing repairs or a leak. Running a water heater without enough water can damage the heating system, and electric models require particular care because their heating elements can fail if they operate without being properly submerged.
If you are wondering should you turn off the water heater when water is off, the safest approach depends on why the water is being shut off and what type of water heater you have. Turning off the main water supply does not automatically shut down the heater, so you may need to switch off its heating source before beginning plumbing work.
Whether you are dealing with a leak, making repairs, or temporarily shutting off the home’s water, understanding when and how to turn off your water heater can help prevent unnecessary damage and make the repair process safer.
Quick Answer: Should You Turn Off Your Water Heater When Water Is Off?
Yes, you should, when shutting off the water to the tank will cause it to drain (or empty). This is a particularly important consideration for conventional, electric tank water heaters.
But you won’t be able to empty a full tank by turning off the main water valve. If you turn off the water even briefly while the tank is full and aren’t doing a repair or drain, the results are different than if you had one.
Follow the manufacturer’s recommendations for your water heater.
What Happens to a Water Heater When the Water Supply Is Off?
Turn off the main water valve for your house so that no more water is entering your plumbing. This won’t get the water that’s already in your regular tank water heater out, though.
Say you shut down the main feed to the tank and the level remains the same. But if someone else opens a hot-water tap, or a plumber disconnects a line, or a customer drains the tank to do some repairs, the level will drop.
That can be significant, because risk is a function of what you do after the water is turned off.
Stay careful with these:
- The plumber must have access to the hot-water line.
- The water heater is going to be drained.
- A plumbing repair could empty the tank.
- The water heater itself is leaking.
- You’re not sure if the tank will remain full.
If there is water releasing from the tank, ensure that the suitable heat source is switched off before you begin working.
What Happens When a Water Heater Goes Out?
When a water heater goes out, the most noticeable sign is usually a lack of hot water. Depending on the cause, you may also notice lukewarm water, unusual sounds, leaking around the tank, or a heating element or burner that is not operating properly. A water heater can stop producing hot water because of an electrical problem, a failed heating component, a pilot or burner issue, or other equipment problems.
However, a water heater not producing hot water does not always mean the unit itself has failed. If the home’s main water supply has been shut off, the heater may still contain hot water, but normal hot-water use is interrupted. If the tank could become drained during plumbing work, the heating source should be shut off as well, especially with an electric tank water heater.
Should You Turn Off an Electric Water Heater When Water Is Off?
Yes, if there’s a risk that an electric tank water heater might be drained, shut the power off.
Once installed, electric tank water heaters rely on heating elements to heat the water. When exposed or left on when the tank is empty, a heating element can be damaged over time, and the following element replacement cost would be a costly upgrade.
How to Turn Off an Electric Water Heater
Complete these broad steps when it comes to shutting down an electric tank water heater (for traditional tank heaters):
- Switch off the power supply for the heater at the correct circuit or disconnect.
- If the tank is at risk of water loss, avoid using the heater until the job is done.
- Do not drain the tank unless necessary for the work to be done.
- Repair the plumbing and turn the cold water back on.
- Open a hot-water faucet to vent air until water steadily flows.
- Test for leaks and ensure that the tank is filled before turning the electric power back on.
Don’t re-energize the power until you know for a fact that the tank is full. If you are uncertain as to whether or not that is the case, don’t energize the power and call a plumber.
You can read about: Can You Lay a Water Heater on Its Side
Do I Need to Turn Off a Gas Water Heater When Water Is Off?
Not always for short water outages. If the tank is completely filled and you are not performing maintenance, turning off the main water feed does not automatically imply that you should turn off your gas water heater.
If the tank is going to be emptied, disconnected, or serviced, disconnect it and turn it off following the manufacturer’s shutdown instructions before starting work. Make sure you don’t follow the same procedure as for electric water heaters since gas appliances operate and require safety conditions differently.
If you have a gas odor, never try to fix the appliance or switch on any electrical switches. Exit the premises and call your gas utility or the local authorities from a safe place.
Can I Turn Off Water and Leave the Water Heater On?
If the tank is full, you could potentially keep a water heater turned on for a brief loss of water, assuming the manufacturer’s instructions allow this. However, you should understand what the plumbing work requires before deciding whether to keep it on.
Here are some cases:
- During a short outage of the water supply, a storage tank is unaffected if hot water isn’t used or plumbing lines aren’t opened.
- Plumbing fix: Please disable first the suitable heating source if a plumber is coming to disconnect pipes or drain the tank.
- Serious leak: Should the leak have the potential to damage the water heater or drain out the water tank, switch off that specific equipment and have an expert get into action.
- If you’re unsure if the tank will stay full or not, the safest bet is to turn off the heating source until verified.
The crucial factor is not just if your main water is turned off. It’s whether your particular water heater will operate safely if it is turned off.
Should You Turn Off a Tankless Water Heater When Water Is Off?
Unlike a storage-tank water heater that heats and stores a supply of hot water, tankless water heaters heat water on demand by passing it through a heating device.
While the exposed tank heating element issue is no longer a problem for tanks without tanks, a tankless heater still needs good water flow and needs to operate.
Depending on the model of the heater, if water is being turned off for plumbing repairs or maintenance, adhere to the manufacturer’s instructions. Do not assume that your electric tank heater’s water shut-off instructions apply to a gas or electric tankless heater.
When Should You Turn Off Your Water Heater?
When would turning off the heat source be a prudent precaution?
Before Draining the Tank
Before draining a traditional tank water heater, always shut it down by following the manufacturer’s directions. Wait for the water to cool, if specified, in order to prevent burns.
During Plumbing Repairs
The water heater may have to be turned off before work begins if a plumber has to open hot-water lines, disconnect the heater, or will be plumbing in a way that could disturb the water level in the tank.
During a Major Plumbing Leak
If you turned off the main water in an emergency for a large leak, find out if the water heater might be in the line. If the leak is coming from the water heater, turn off the proper water and energy supplies as the owner’s manual tells you, and call a plumber.
Before Water Heater Maintenance
Tasks such as flushing, draining, replacing components, or disconnecting the unit require the correct shutdown procedure. If you are not sure which controls to use, ask a qualified plumber rather than guessing.
How Do You Turn the Water Heater Back On?
Some notes before we begin: this is the process for how to restart a tank water heater normally. Process for how to restart a traditional tank water heater:
- Finish the plumbing repair.
- Confirm that any drain valve is closed.
- Restore the cold-water supply.
- Open a hot-water faucet and keep releasing the air until you get a steady stream of water.
- Examine the heater as well as the surrounding connections for leaks.
- Confirm that the tank is completely full.
- Don’t turn the power back on to your electric heater until you’ve confirmed that it is full.
- How To Reset A Gas Water Heater: Simply do what the manufacturer instructs you to do.
Do NOT turn back on the electric tank water heater because you see water dripping into the sink. If you are wondering if the tank is filling, simply keep the power off until you’re positive it’s filled.
What Mistakes Should You Avoid?
- There are some avoidable errors that can cause end users big harm or safety issues.
- Applying electrical power to a water heater too early: When there’s no water present, many of the system’s heating elements will blow and burn out.
- Water in the tank could be hot and cause severe burns.
- Electric tank, gas tank, hybrid, and tankless will have specific pre-requisite.
- The way to shut down and restart can be different depending on the model.
- Attempting to estimate the tank is full: Leave the power off to an electric tank heater unless you know it’s full.
When Should You Call a Plumber?
There are times when simply turning off a switch or valve won’t do the trick. Here are a few instances where calling a licensed plumber may be a better option:
- Your water heater is leaking.
- The tank does not seem to fill up again.
- You cannot identify the correct shutoff controls.
- The heater can start again once water flow has resumed.
- You hear unusual sounds after restarting it.
- In a plumbing repair, the heater can be drained or disconnected.
- You cannot tell if your electric tank is full.
For proper installation of your water heater if your unit is damaged or needs to be replaced, call our professional water heater installation in Eagle Rock.
Professional Plumbing Services in Eagle Rock
No matter the case, you don’t want to tackle a water heater leak or water supply disruption until you understand what is going on with your plumbing. Water heater services in Eagle Rock with support for tank and tankless.
In case you aren’t sure if your water heater needs to be turned off or not during a repair, a professional plumber can evaluate the circumstances and recommend your best option. Check us out at Derks Plumbing.
Key Takeaways
- Turn off the water heater’s heating source if the tank could be drained or lose water during plumbing work.
- Electric tank water heaters need particular care because their heating elements can be damaged if they operate without enough water.
- Shutting off the main water supply does not automatically empty a full storage tank.
- Follow the manufacturer’s shutdown instructions before draining or servicing a water heater.
- Confirm that an electric tank is completely full before restoring power.
- Gas, electric, hybrid, and tankless water heaters have different operating procedures.
Conclusion
So, should I turn the water heater off when the the water is off? For most domestic water heater systems, the answer is yes when planning to work on the system and cause a depletion of the water supply.
The key safety tip for electric tank water heaters is to ensure that the tank is full before you turn the power back on. With gas and tankless models, the safety tip will vary; just follow the steps for your model.
A water shutoff, plumbing repair, or water heater leak can be confusing when you don’t know what to turn off. Derks Plumbing can evaluate the situation and find the service required.
Frequently Asked Questions
You may be wondering if you should be switching off the water heater when you aren’t going to be using any water.
As a general rule, if your water supply is turned off and the tank has drained or will drain there is no need to have the heat source turned on. This applies to most types of water heater tanks; however, conventional electric tank water heaters require the source of heat to be turned off.
Do you turn off the water heater when not in use?
Not always at every short interruption. If the tank is kept full and no maintenance is being performed, it is going to be a different case from a tank that will be drained or disconnected. Follow manufacturer instructions for your model.
Can you turn off an electric water heater when the water is turned off?
Only if the tank is totally full and the manufacturer says that it is okay to use normally with the tank full. If the tank is losing water, the electrical supply should be turned off to help avoid damage to the elements.
If you turn off the main water but leave the water heater on, what occurs?
Hot water in an existing tank stays in the tank when the supply is cut off. If hot water or opening of plumbing lines is used, they can empty the tank. If an electric tank of hot water goes down empty and is turned on, the elements can be burnt.
Can I turn my water heater off when not in use?
A normal water heater doesn’t usually require turning off for a brief amount of time you’re not utilizing warm water. If you plan on remaining away from house for a few days or very long, check with the manufacturer for any vacation or low-temperature establishing.
How do I safely turn my water heater back on?
Restore the water supply, fill the tank, turn on a hot-water faucet to bleed any air from the tank, and search for leaks. Restore the power only after the electric tank fills. Follow the restart instructions for the gas model.
Should I turn off the water heater before plumbing repairs?
In most cases, if the service requires draining the tank, opening hot-water lines or service involving the heater itself, the heating source should be turned off first. This varies depending on the type and model of water heater.
Can turning the water off ruin a water heater?
Yes, it can, depending on the style of heater and what is done after the supply is turned off. Electric tank water heaters can also be toast if the elements come on without enough water to keep them cool.
