Water heaters come in many types, shapes, and sizes. Choosing the right model for your home or business begins with asking the right questions. How much hot water do you need? How many people will your water heater serve? What is the best energy source for heating your water? What type of water heaters are the least expensive to run? The chart below can help guide you on the path to selecting a water heating system that best meets your needs. For more intormation visit energy.gov.