A traditional tank heater lasts 6 to 10 years, and its efficiency decreases every year as sediment accumulates at the bottom. If you select the right size tankless water heater and have it installed professionally, you can rely on it twice as long as a tank heater.  And if you ever do experience a problem, a tankless heater is serviceable.  A broken tank heater can rarely be fixed, only replaced.  Want to know what a tankless heater costs? »