There is no definitive answer to this question as there are a number of factors that can affect the likelihood of a hot water heater exploding. However, it is generally considered to be a relatively rare event. There are a number of safety features built into most hot water heaters that are designed to prevent an explosion, such as pressure relief valves and temperature sensors. Additionally, hot water heaters are typically installed in areas where they will not cause significant damage if they were to explode, such as in basements or utility rooms.