I'm not sure the size of our tank but the hot water runs out quicker during the winter months than the summer with the same water usage. During the summer we have almost endless hot water then in the winter we have about 5 minutes before it starts to get cool.

And would this be a gas or electric heater? How far is it from your bathroom? The average size is 40 gallons so unless you tell me otherwise that's your size. Howe many in your family? How many kids or young females? Are any hot water pipes located on a outside wall? Back to you, Tom