My hot water heater is about 15 years old. The water heater has never required any repairs and has operated well for 15 years, which I do appreciate. At the time I bought it, the manufacturer had promoted it as energy efficient, and it might have been for the time. However, I think our standards of energy efficiency have changed over time, and I do worry that the water heater is costing me a lot of extra money as it is so old. The whole idea of having to heat water even when you are not using it seems wasteful to me. The only other issue I have with the water heater is that it is somewhat inconsistent. Sometimes my water is pleasingly hot and at other times it is more or less tepid. I think it has to do with where the heater's thermostat is and the heating cycle. I would wish for more consistency in water temperature. If I had to replace this water heater, I believe I would look into one of those on demand hot water heaters. If that did not prove reasonable then I would look for the features of energy efficiency, reliability, and consistent water temperature.