Water heater warranties range from three to 12 years and, typically, you get what you pay for. Longevity depends upon the tank lining, water quality, and other factors. Most people replace their water heater in a crisis, when they discover that its not producing hot water or is leaking. If your water heater is out of warranty, it is living on borrowed time.
How can you determine your tank’s age? Check out its serial number, says Home Energy magazine. “If it begins A-83 or 0183, the tank was built in January 1983. B-83 or 0283 mean February 1983, and so on. If it begins 8301, the tank was built in the first week of 1983; 8352 would mean the last week of that year.”