1. 25% of every household energy dollar is spent making domestic hot water.  Heating water with a conventional tank is the third largest energy consumer in your home (behind furnace and A/C).
2. Electricity is the WORST way to heat hot water while natural gas and propane gas are much more efficient. Based on national fuel price averages of $1.46/ccf and $0.09/kwh, the cost/100,000 BTU’s is $1.46 for natural gas and $2.64 for electricity. Just under 60% of North American households have access to natural gas, and if you don’t, propane gas is available to almost everyone and is still a better value than electricity. In addition electric water heaters have only a small fraction of the capacity of gas water heaters. So if you like expensive, short showers, with cold water at the end, use electric; otherwise gas would be a better choice.
3. Modern gas fired tankless water heaters are the best alternative available to today’s homeowners to reduce their residential energy consumption. A typical gas fired tankless water heater cost about 2-1/2 times as much as a standard tank water heater. However it will pay for itself in just a few years or less, and will last twice as long as a tank.
4. If you are considering a tankless water heater Rinnai is likely the best choice. On average a new Rinnai is installed somewhere in North America every 3.75 minutes. Rinnai has shipped over 30 million tankless water heaters world wide.

See Also:

1. What is a Tankless Water Heater?
2. Descaling Your Tankless Hot Water Heater
3. Tankless From Us?