Its worth noting that you can combine an on-demand (tankless) hot water system with at tank. The on demand system heats the water and stores it in the tank (whi

Its worth noting that you can combine an on-demand (tankless) hot water system with at tank. The on demand system heats the water and stores it in the tank (which is not a water heater). The tank itself, since it has no heating elements, can be _very_ thermally efficient. You get the benefits of both systems (though it does cost more to install, obviously)