Natural gas is supplied to many homes in the United States by way of underground piping. Liquid Propane (LP) is used mostly in rural areas of the country, where natural gas is not available. LP gas is usually stored in large tanks that sit in your yard. The gas is typically delivered to your home in a tanker truck and pumped into the tank sitting in the yard. Most A. O. Smith gas water heaters are available from the factory in either liquid propane or natural gas. Both fuel sources can provide consistent hot water for your home.