If you like a long shower or have multiple people taking a shower one after the other, 67gallons might give you 1/2-hour of total running time before you end up with a cold one. And, throughout the second half of that, you might be turning the hot up to keep it warm. That's not very much supply, but may be sufficient if you are frugal. You certainly wouldn't want to be running the dishwasher or a washing machine with warm or hot at the same time. It would be hard pressed to fill a soaking tub, but might, depending on the size and how hot you run it.