What would cause a Water Heater Explosion? How to prevent it


Hey there, have you ever thought about the trusty water heater lurking in your home? It’s that silent hero giving you that cozy hot water for showers, washing dishes, and getting your laundry done. But guess what? There’s a rare but pretty scary thing we need to talk about: Water heater explosion.

Don’t worry, we’re not here to scare you, but it’s essential to know what could go wrong and how to keep it from happening. So, in this article, we’re going to teach you in detail about water heater explosions. You’ll learn about why they happen (even if it’s rare), how to spot the warning signs, and, most importantly, how to make sure it never happens in your home.

Home safety is a big deal, and being clued in on the potential risks with your water heater is just a smart move.

Understanding Water Heaters

Before getting directly into the reasons for water heater explosions, it’s crucial to understand how water heaters function. Most residential water heaters use either gas or electricity to heat water. A typical water heater consists of a tank, a heating element (for electric heaters) or a burner (for gas heaters), a thermostat to regulate the temperature, and safety features like pressure relief valves and temperature-pressure relief (TPR) valves.

  1. Cold Water Inflow: The process begins when cold water enters the water heater through a pipe connected to the unit. This cold water is typically fed from your home’s main water supply.
  2. Storage Tank or Heat Exchanger: In traditional tank-style water heaters, the cold water flows into a storage tank. This tank is heavily insulated to retain heat and comes in different sizes, usually ranging from 30 to 80 gallons. In tankless (on-demand) water heaters, there is no storage tank; instead, the water flows through a heat exchanger where it gets heated on the spot.
  3. Heating Element or Burner: In electric water heaters, a heating element heats up the water inside the tank. These elements work similarly to the coils on an electric stove. For gas water heaters, a burner at the bottom of the tank is responsible for heating the water. It’s fueled by natural gas or propane.
  4. Thermostat: Regardless of the heating method, both types of water heaters have a thermostat. This thermostat allows you to set the desired water temperature. It regulates when the heating element or burner turns on and off to maintain the water at the chosen temperature.
  5. Heat Transfer: As the heating element or burner does its job, it warms the water inside the tank or heat exchanger. The hotter water rises to the top of the tank, while colder water settles at the bottom. This process continues until the entire tank is at the set temperature.
  6. Safety Features: Water heaters are equipped with safety features like temperature-pressure relief (TPR) valves. These valves are crucial because they release excess pressure and hot water to prevent the tank from becoming over-pressurized, which could lead to a dangerous situation.
  7. Hot Water Outflow: When you turn on a hot water tap or appliance in your home, hot water is drawn from the top of the tank and is sent to where it’s needed, whether it’s your shower, sink, or dishwasher. In tankless water heaters, the water is heated as it flows through the heat exchanger on its way to the tap, providing hot water on demand.
  8. Cold Water Inlet (Again): As hot water is drawn from the tank, cold water replaces it to maintain a consistent volume of water in the tank. This ensures that you have a continuous supply of hot water.

What Causes Water Heaters to Explode

1. Excessive Pressure Buildup:

Water heaters operate by heating water and expanding it within the tank. To accommodate this expansion, water heaters have a relief valve that opens to release excess pressure. However, if this valve is malfunctioning or blocked, pressure can build up to dangerous levels. Excessive pressure can weaken the tank’s structural integrity, leading to an explosion.

Helpful topic: Do you need expansion tank for tankless water heater

2. Sediment Buildup:

water heater sediments formation

Over time, sediment, minerals, and debris can accumulate at the bottom of the water heater tank. This buildup can insulate the heating element or burner from the water, causing it to overheat. The extreme heat can lead to water boiling within the tank, producing steam and even more pressure. If this pressure is not relieved, it can cause an explosion.

3. Corrosion:

Corrosion can weaken the tank’s walls and make it susceptible to rupture. Water heaters are constantly exposed to water, which can cause rust and corrosion over time. If the corrosion is left unchecked, it can eventually lead to a breach in the tank and a potential explosion. Some times corrosion causes holes on tank and tends to leaks in water heaters.

4. Faulty Temperature and Pressure Relief Valve:

Every water heater should be equipped with a properly functioning temperature and pressure relief valve (TPR valve). This valve is designed to open and release water if the temperature or pressure inside the tank becomes dangerously high. A malfunctioning or blocked TPR valve can result in a catastrophic failure.

5. Overheating:

Setting the thermostat on your water heater too high can cause the water to overheat at high temperatures. This not only wastes energy but can also increase the pressure inside the tank. If the TPR valve fails to open, it can lead to an explosion.

6. Gas Leaks (For Gas Heaters):

Gas water heaters rely on a burner to heat water. If there is a gas leak near the heater and it ignites, it can result in an explosion. Gas leaks are especially dangerous due to the risk of fire or explosion.

The Risks of a Water Heater Explosion

A water heater explosion can result in serious consequences:

  1. Property Damage: An exploding water heater can cause extensive damage to your home, including flooding, structural damage, and damage to personal belongings.
  2. Injury or Death: People nearby can be severely injured or killed by flying debris or scalding water.
  3. Fire Hazard: If the explosion is accompanied by a gas leak, it can lead to a fire, further increasing the risk to life and property.

How to Prevent Water Heater Explosions

To prevent water heater explosions and their associated risks, consider these preventive measures:

  1. Regular Maintenance: Schedule annual maintenance for your water heater, including flushing the tank to remove sediment and inspecting the TPR valve.
  2. Temperature Settings: Set the thermostat to a safe and efficient temperature (around 120°F or 49°C) to avoid overheating.
  3. Pressure Relief: Ensure that the temperature and pressure relief valve is functioning correctly by testing it periodically.
  4. Expansion tank: Install an expansion tank which absorbs the thermal expansion of the water when its heated and reduces the pressure inside the tank to maintain its safe levels of pressure.
  5. Address Corrosion: Regularly check the anode rod which is responsible for the control of corrosion of the tank. If you notice signs of corrosion on your water heater, consult a professional for an evaluation and potential replacement.
  6. Proper Installation: Have your water heater installed by a qualified technician with good experience to ensure it meets safety standards.
  7. Gas Leak Detection: If you have a gas water heater, install gas detectors in your home and schedule regular gas system inspections.


A water heater explosion is a rare but potentially catastrophic event. Understanding the causes and risks associated with water heater explosions is crucial for homeowners. Regular maintenance, proper installation, adding expansion tank for extra safety and vigilance can significantly reduce the likelihood of such an event. By taking these precautions, you can ensure the safety of your home and loved ones while enjoying the benefits of a reliable hot water supply.

TanklessHelp Staff

TanklessHelp Staff has an experienced writers and researchers in the field of water heating technology. With a background in HVAC and plumbing, Tanklesshelp staff has in-depth knowledge in many types of waterheaters in America and Canada. They have a passion for educating homeowners and businesses on solving easy to hard repairs and guide them on how to maintain them to save money.

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