Can a water heater explode?

water heater in a utility room

Getting a Water Heater Inspection

Well, can a water heater explode? Can a water heater leak gas? Yes and yes! When a water heater is under excessive pressure it could explode and if a water heater has a gas leak, it could explode. These are a couple of reasons you want to have an annual water heater inspection performed. Other things that can cause a water heater to explode is the anode rod, or sediment buildup.

To understand how these can cause a water heater to explode, let’s review how a water heater works, the one common appliance every home has! This big metal cylinder may look simple and ordinary on the exterior, but inside, there is a lot going on. 

Most water heaters are installed in a basement or the laundry room, or today, you can have a tankless water heater that allows it to be installed in more places. In this piece today, we’re going to focus on the old-school tank-style water heater. The tank is filled with water and there is a heating mechanism inside that tank too, along with several other components, all of which are checked during a professional water heater inspection: 

  • Dip tube – Located at the top of the tank, the water enters through this and sends it to the bottom where it is heated.
  • Shut-off valve –This component is located outside of the tank, usually at the top, and shuts the water off to the water heater. 
  • Heat-out pipe –Suspended at the top of the tank inside this allows the hot water out of the tank. 
  • Thermostat – The thermometer is device that controls the temperature. Electric water heaters are two, one for each element. 
  • Heating element – There are typically two of these in electric water heaters that heat the water. 
  • Drain valve – Located the bottom of the tank, on the exterior housing, the drain valve allow the water to be emptied so that water heater repairs can take place, like replacing the elements, and flush sediment from the tank. This is also used to drain the tank to move it or replace it. 
  • Pressure relief valve – The PRV is a safety device that keeps the pressure safe inside the tank. 
  • Anode rod – Made of aluminum or magnesium, this has a steel core and is suspended inside the tank to minimize corrosion. 

All of these components are necessary for the water heater to function, starting with the thermostat controlling the water temperature inside the tank. Normally, the temperature is set 120 degrees but can be set at 180 degrees. The dip tube takes the water piped to the tank and feeds it to the bottom of the tank. There it is warmed up by the heating element. The heating elements will stay on until the water reaches the desired temperature. 

The water rises to the top of the tank as it heats, it rises to the top of the tank. As we learned in 8th grade science, hot water is lighter than cold water. From there, the heat-out pipe, located near the top of the tank and separates the hot water from the cold water, which has sunk to the bottom of the tank. 

Can a water heater leak? 

Yes, water can leak from the connections of the water heater or from the tank itself. A professional water heater inspection can catch things like loose connections, tighten them up, and stop any possible leaks. A water heater inspection also will check all the components on the exterior and interior of the tank, as well as the tank for possible small leaks.

What does a water heater inspection consist of?

During a professional water heater inspection, the plumbing technician will check the following for indication: 

  • Corrosion
  • Leak
  • Weak areas 
  • This includes checking the water lines and vents. 

What are the signs your hot water heater is going out?

Any of the following are abnormal for a water heater and typically are indications a new unit is needed.  In some cases, having a professional water heater inspection first will confirm that a repair is sufficient: 

1. Wet around or outside the tank: Condensation or moisture on the exterior of the tank often is from a slow leak. It can also mean there is a small leak on the tank, and in either case, you should have a professional water heater inspection to confirm there is a problem. 

2. Rust forming on or around the tank: If you see dark red or orange rust coming from the tank or the faucets, your water heater is full of corrosion. If the water smells metallic, this also indicates rust inside the tank. It is beyond water heater inspection, and time to replace the unit. 

3. Loud or unusual sounds: If you hear loud, strange, or unusual sounds coming from the tank, a water heater inspection could find that flushing the unit or replacing the anode rod is a quick fix. Most of the time, replacing the unit is recommended, based on the age of the water heater. 

4. Insufficient amount of hot water: If the water isn’t getting hot enough or there isn’t enough hot water to complete a shower, you need to replace the unit. 

Should I repair or replace my water heater?

First, determine the age of your water heater. Once they reach 10 years old and have any of the issues listed above, replacement is recommended. Have a professional water heater inspection to resolve any doubt of which is the best method for you. 

What water heater do I need?

If a water heater inspection reveals that you need a new water heater, the same technician can help you determine the best size based on the needs of your household. With a traditional tank-style water heater, the following will give you an idea of what size to purchase:

  • Up to  2 people—23 gallons to 36 gallons
  • 3 to 4 people—36 gallons to 46 gallons
  • 5 people—46 gallons to 56 gallons
  • 6 or more  people—add 10 gallons after 56 gallons for each additional person

Which water heater is most efficient?

Choose a brand that is ENERGY STAR rated. With a gas-powered water heater, the energy factor should rate 0.67 and 0.70. If you’re buying an electric water heater, choose a high-efficiency water heater. These extract heat energy out of the exhaust gases for heating the water, and some include a secondary heat exchanger. This provides a maximum in the heat transfer process by extracting as much heat energy from the whole combustion process.

close-up of a shower head spraying hot water

Closing Question 

With a gas water heater, is it dangerous if the pilot light goes out on the water heater? In most cases, an extinguished pilot isn’t dangerous. Today, gas-powered water heaters have a valve that automatically closes the gas supply off when the pilot light goes out.