While there are some water heaters that run on solar energy, oil and propane, the most common water heaters are fueled by either electricity or natural gas. With electric water heaters, the water is warmed up when it comes in contact with large coils extending into the tank. Natural gas water heaters use a burner to heat up the water tank. Whether you need to replace the water heater in your existing home, or just don't know what kind is in your basement, there are several ways to determine whether your water heater is electric or gas.
Remove the access panel on the side of the water heater and look inside for a blue flame. This is called a pilot light and indicates the presence of natural gas. If you see a pilot light, you have a gas water heater. Electrical water heaters do not have pilot lights.
Look at the top of the heater for an electrical supply cord. This looks like a thick extension cord and is generally black or gray. If you see one going into the top or side of the heater, it is an electric water heater.
Search for a black pipe going into the bottom of the tank. This is generally about ½-inch thick and black. This is a gas pipe and indicates that your water heater is gas powered.
Identify a copper pipe going into the bottom of the tank, as long as you don't see a black gas pipe. The pipe will be about ¼-inch thick. If you see that, it means you have a gas water heater.
Look for a vent pipe on top of the water heater. The presence of a 3- or 4-inch PVC pipe indicates a gas water heater, because the fan and motor inside the water heater force exhaust created by the gas out into this vent and outside. Electric water heaters do not have a venting system as there is no exhaust.