Water heater size is based on the number of people in the home, so if a four bedroom home has five people, the minimum size water heater would be 50 gallons. However, if the water heater is electric, a minimum of 80 gallons is recommended.
In addition to the size of the water heater, a homeowner may also want to consider space and fuel type. Water heaters are available in electric, gas, solar or heat pump/hybrid forms. All of these have pros and cons, so research may be in order. When considering space, the water heater must fit in the designated area, so homeowners are advised to take measurements before shopping.