Inhabitants

• According to Consumer Reports, an adult uses double the amount of hot water to bathe that a child uses. In addition, adult baths use about 20 percent more hot water than adult showers. If you have adults in your home who bathe often, account for that in your water heater size decision. In addition to adult versus child bath water usage considerations, the overall number of people in your home impacts how many dishes you wash, loads of laundry you do, and hands that are washed.
  
  

Appliances

• The California Energy Commission says that front-loader laundry machines reduce the water used by almost 40 percent, compared to top loaders The other appliance in the home that uses hot water is the dishwasher; newer dishwashers use about 30 percent less hot water than models over 10 years old, and are about 25 percent more hot water efficient than washing dishes by hand.
  
  

Fixtures

• If your home has older water faucets and shower heads, you may be using too much hot water. Consumer Reports states on its website "you can purchase some quality, low-flow fixtures for around $10 to $20 apiece and achieve water savings of 25 to 60 percent." Therefore, a minimal investment in new fixtures may reduce the capacity you need in a new water heater, consequently saving a minimal amount on the cost of a new water heater.