Unfortunately there is no easy answer to the question of how long a water heater should last. As a plumbing service company, Plumbing Professors technicians have seen water heaters over 25 years old still doing a fine job, and heaters 2 years old that produced no hot water. First let's understand the two main types of water heaters. CONVENTIONAL WATER HEATERS (Gas or electric): As general rule, the conventional water heaters of today are considered "old" when they hit their teenage years. Read More >