Should I Turn off my Water Heater if the House Water is Shut off?

water heater valve

Are you wondering if you should turn off your water heater if the house water is shut off? You’ve come to the right place. Below, I’ll share a few things you should know about your water heater. 

Yes, you should turn off your water heater if the house water is shut off for an extended time. Your water heater has a tank that contains water. As long as you don’t use the water, it stays in the water heater (this depends on the type of water heater). If, for any reason, the water levels fall in the tank, then it’s best to turn off the water heater. 

Like anything in life, the discussion on when to turn off your water heater has nuances. In the sections below, we’ll unpack several scenarios and discuss how to handle them. 

These days, there are many types of water heaters and plumbing systems. Want the best advice? Find your water heater’s manufacturer and give them a call. Ask them what your water heater can and cannot handle. 

Why Should You Turn Off Your Water Heater When the Main Water is Off? 

If you’ve ever set a full plastic water bottle in a fire, you’ll know that the plastic doesn’t melt. This is surprising to most people and leads many to wonder: what’s going on? Essentially, the water dissipates the heat and prevents the plastic water bottle from melting. 

If a plastic water bottle were placed in a fire without water inside, the plastic would begin to melt (note, we’re not suggesting you place plastic in a fire! This can create dangerous fumes). 

The same thing happens with traditional water heaters. The interior of the water heater is often coated with components that can burn up if there’s no water in the tank. In fact, some professionals site water loss in a water tank as one of the primary reasons they blow up.

How Do Water Heaters Work? 

Water heaters come in all sorts of configurations. This section will talk about the general configuration of traditional water heaters. 

For our purposes, we’ll talk about four components: the heater, the tank, the incoming water supply, and the outgoing water line. 

The heater itself may use gas or electricity to heat the water. The tank is what holds the water. The tank works with the heating component to have gallons of hot water ready when you need it. When you turn on the hot water, the hot water leaves through the outgoing water line, and cold water refills the tank, and the heater begins heating again. 

Often, the inner tank will have a corrosion-resistant coating. If the tank gets hot but there’s no water, the coating could become damaged. 

We’ve just described a water heater that uses a tank; however, some water heaters are known as tankless or instant

Tankless Water Heaters 

Tankless water heaters have two advantages. First, they don’t have a big supply of water that takes a lot of energy to heat and risks leaking. Second, instant water heaters provide a near-endless supply of hot water, unlike tank systems which can become easily overloaded with too much use. 

Should you turn off a tankless water heater if the main water is off? Well, it’s less important than turning off the regular water heater. It’s up to you and the manufacturer. Some tankless water heaters may benefit from being turned off, but for most, it isn’t an issue. 

In general, if you’re leaving the house dormant for a while, then turning off all appliances is a good practice. 

Should You Turn off Your Water Heater for Repairs? 

If you’ve turned off the main water line to make a repair, you’ll need to consider two main things. 

First, is the repair related to the water heater? If you’re making a repair directly to the water heater, then yes, it’s probably prudent to turn off the water heater as well – especially if the repair involves anything with the electrical system or the gas supply. 

However, if you’re making a plumbing repair that is completely non-related to the water heater, then there’s no reason to mess with the whole system. With that said, there is one exception to this. 

If, for some reason, you could be draining the water heater during the repair, and the repair could extend for a day or so, then turn off the water heater. You don’t want to risk draining the water from the tank with no water to refill the system. 

Should You Turn off Your Water Heater While on Vacation? 

Most people know that it’s wise to turn off the water to the house if you’re leaving for an extended vacation. Turning off your main water keeps your home safe from extensive water damage. Why? Just think, if there was even a tiny leak, if the house water is on, that leak could flood the entire house. 

So, people often wonder if turning off their water heater is also an important step of home safety during vacation or extended absences. Let’s start with this: turning off the water heater is not as important as turning off the house water. 

However, if you’ll be away for an extended period, then it’s probably prudent to turn off the water heater also. Why? Because, though the cost may be minimal, you’re still spending money on keeping water warm when nobody will be using it. 

With that said, there is another option: vacation mode. 

Most water heaters allow you to turn the unit to “Low” or “VAC” this turns the heater down considerably, saving you energy while also preventing a lengthy start-up process. 

Why Some People Avoid Turning Off Their Water Heaters Even With the House Water Off

Some people are averse to the idea of ever turning off their water heater. The reason? Hot water heaters, particularly traditional water heaters with a tank, require some jump ropes to get started again. 

For one, you often need to start a pilot light. The pilot light aids in heating the unit. Sometimes, the pilot light is easy to light. Other times, lighting a water heater pilot light can be a real pain! This can depend on the unit’s location – if the water heater is in a dark, dank basement, it will be more difficult to get it started. 

Second, you’ll have to wait a while for hot water. This will depend on the unit’s efficiency, but nobody likes cold showers – the whole point in having a water heater is to have hot water.  

If you need to turn off your water heater, we’ll talk about how to do this in the next section. 

How Do You Turn off Your Water Heater? 

There are several times you should always turn off a water heater, such as if the water heater is leaking, or if you’ll be away for several weeks. So, in this section, we’ll go over the steps required to turn off a water heater. It’s always best to follow the manufacturer’s guidelines, as every water heater is a little different in its setup. 

Here are the steps to turn off a water heater: 

  1. Cut the gas or electricity 
  2. Turn off the incoming water valve 
  3. Drain the water 

Time to look at these steps closer. 

Note: have a look at your hot water heater before the emergency. This will ensure you’re prepared. 

  1. Cut the Gas or Electricity to the Hot water Heater 

You can usually turn off the gas with a switch nearby the water heater. There is usually a simple valve that needs to be turned off. However, depending on the situation, you may also want to cut the gas supply to your house to prevent carbon monoxide gases in your house. 

To cut the electricity, you should have the switch marked at your main breaker. 

  1. Turn off the Incoming Water Supply

The incoming water supply fills the water heater with a steady supply of cool water. If you notice the water heater leaking, then turning off the water supply is one of the first steps. 

Usually, the incoming water supply has a valve near the water heater that allows you to cut the supply to your water heater completely. 

  1. Drain the Water to Your Water Heater

After you’ve turned off the water supply to your water heater, you may need to drain the water – especially if you need to replace a damaged water heater. 

Near the bottom of the water heater, you’ll find a spout to drain the water. This spout can be routed into a floor drain. Here’s a video that explains how to turn off the water heater

Now for our final word.

Key Takeaway on Turning Off the Water Heater When the House Water is Shut Off

Always turn off your water heater if you suspect it is leaking or if it is near failure. Water heaters that are going bad will make strange noises, or you may notice abnormalities in your hot water. 

You don’t always need to turn off the water heater if your house water is off; however, you should turn off the water heater if you’ll be gone for extended periods or if you’re making repairs to the water heater itself.