Can You Leave the Water Heater On When the Water Is Off?

The design of water heaters has evolved throughout time. The large tanks have been replaced with more compact and effective models.

Their designs have become as accident-free as possible. The primary reason for this is that the heaters are mostly tankless. 

So, can you leave the water heater on when the water is off?

Yes, even when the water is off, it’s safe to leave the water heater on. In some instances, though, turning off the main water supply could be a safer option, especially if there’s a plumbing issue.

Completely cutting off power sources could also work in some instances. 

This article discusses when you should leave it on and the circumstances that require you to switch it off.

Can You Leave the Water Heater On When the Water Is Off?

Should you turn the water heater off if there is no water?

On most occasions, leaving the water heater on is safe and advisable even when the water is off. So, when do you need to switch it off?

Turning off the water heater keeps too much heat or pressure from building up in the tank. When it happens, consider if it’s safe leaving the heater on or off. 

When Would You Need to Turn Off the Water Heater?

You need to turn off the water heater if:

Your Main Water Supply Is Off

Most of the time, it’s okay to leave it on when the main supply of water is off. There are exceptional cases that may call for turning off your heater. Such instances include:

  • If your water tank is almost empty or empty and there’s no plan to refill it soon. Having the water heater run on an empty tank risks building up pressure or damaging the unit.
  • When there’s low pressure from the main supply of water. Running at low water pressure means you risk damaging the tank or a potential explosion. 

Leak in the Water Heater

Having a leakage in the water heater can be risky in some scenarios. Ensure you let it stay off until you’ve identified the problem as you look for an expert who can handle the problem professionally. 

Below, however, are reasons why your water heater is leaking:

  • Degraded part(s)
  • Malfunctioning of a valve
  • Heater’s age — being too old.

Cutting Down Water Heating Costs

Some people choose to switch off the heater to reduce water heating costs. However, this may cause you more problems than save you money. Why?

You may experience challenges when turning on the water heater again. 

When You’re Off for a Vacation

If you’ll be away for many days at a time, adjusting the water heating system is one of the routines you’ll need to keep in place. Therefore, switch the water heater to “vac” mode. 

This setting is typical with the new-age water heaters. If that’s not the case with yours, lower the water temperatures. 

How to Switch Off an Electric Water Heater

Electric water heater turned on without water
  • Start by disconnecting the heater’s source of power. This is a safe way of ensuring somebody doesn’t switch it on.
  • Regardless of how long you’ll be away, ensure you’ve cooled the water fully. The same applies when you want to repair the water heater. It helps implement the shutting down process and makes it safe when conducting repairs.
  • Proceed by turning the water off — use the cold water valve.
  • Next, empty your water tank fully. Not only is it essential when you’re away for long periods, but it’s also critical to drain the tank once in a while to help in flushing out sediments. 


Can I Shut Off the Water to My House and Safely Leave the Water Heater on While I’m Away on Vacation for a Week?

“Vac” mode drops the water heater temperatures to conserve energy while not in use.

So, if you’ll be traveling for a couple of days, set your heater to vacation mode. Some models, though, may not have this option. The best you can do is to set the water temperatures to the lowest setting. 

Once you’re back, turn the heater back to the usual setting, and you’re good to go.

Should I Turn Off My Water Heater When Not In Use?

No, you shouldn’t turn off the water heater when not in use unless you’re going to be away from your home for three days or longer.

Also, you may turn off the heater if there’s a mechanical problem that needs to be professionally corrected.

Otherwise, you’ll only create more problems by repeatedly turning the water heater on/off. 

Can Water Heater Explode If Turned Off?

If too much pressure builds up, the water heater can explode. Turning it off prevents such occurrences.

Therefore, once you notice that the valve is leaking, there’s too much pressure inside the water tank. Accordingly, you should turn off the water heater immediately. 

Should the Water Heater Always Be On?

You can turn off the water heater occasionally, especially if you’re going to be away from your home for a while. It not only helps you keep your home safe but also helps you conserve energy.

Is It Ok to Leave a Hot Water Heater on Pilot?

When flushing, you can have the water heater on the pilot mode. This prevents cases such as the burner switching on while there is no water in the tank.

This could adversely destroy the water tank. 

Should I Turn My Water Heater Off at Night?

It’s best to leave the heater on throughout rather than switching it on and off.

In addition, if the hot water tank has proper insulation, it’ll keep water hot throughout the day, and there’ll be no need for reheating. 

Final Thoughts

In most cases, you’ll not need to switch off the water heater when the water is off. However, if you’re experiencing issues with the main supply of water, then you’ll have to switch off your heater.

Contact a reputable plumber when unsure of the next course of action.

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