Water Heaters

I am building a new house and wanted to know what size water heater should I buy?
Usually people base their water heater purchase on the size of the storage tank. A better method is to first estimate how much hot water you will need during the peak hour of use. This is referred to as the first-hour rating (FHR) on the Energy Guide label posted on new water heaters.

Typical hot water use is:

Bathing 15-25 gallons per bath
Cleaning house 5-12 gallons
Food preparation 1-6 gallons
Running clothes in the washer 25-40 gallons
Running dishwasher 5-20 gallons
Shaving 1-3 gallons
Showering 3 gallons per minute
Washing Dishes 4-6 gallons
Washing hands ½ to 2 gallon