As of 2015, gas water heaters typically cost a bit less than their electrical counterparts and are cheaper to run. Water heating is a major component to energy bills, and homeowners with access to gas lines can quickly recoup any extra cost associated with gas water heater installation.
Electrical water heaters are more efficient than gas units, but this efficiency can be deceptive. Power plants lose a significant amount of energy when electricity is converted to heat. Because of this, using the heat generated by combustion in gas water heaters directly leads to better efficiency and, in most places, lower energy costs.
Gas water heaters can cost more to install since they need a connection to a gas line, and the cost of installing pipes appropriate for handling natural gas is typically more expensive than electrical work. Gas water heaters typically provide faster heating, which may allow homeowners to use a slightly smaller units.
Many tankless water heaters are powered by natural gas, which is capable of generating heat fast enough to keep up with even heavy use. Tankless systems are significantly more expensive than traditional units, and they might require expert installation. Estimating cost saving depends on knowing how long tankless systems last, which can be difficult since they are still relatively new.