Based on the manufacturer's suggested service life, the life expectancy of a water heater is about eight to 12 years. That varies with the location and design of the unit, quality of installation, maintenance schedule and water quality. If your water heater is more than 10 years old, leaks around the base of the tank or if it works erratically, it's probably time for a replacement. You may also choose to upgrade to a more efficient model to cut your energy expenses.
In some cases, repairs and troubleshooting can save your existing water heater. Before you look for a replacement, make sure that an electrical problem, such as a blown fuse or tripped breaker, isn't the reason for the unit's failure. Regular water heater maintenance will extend the life of your unit, and some repairs such as replacing a pressure relief valve or heating element are pretty simple.