My Whirlpool 52 gallon, 12 year guaranteed heater, failed
after 3 years, so age sometimes doesn't count.The original
Rheem copper lined tank lasted 20 years, that was installed in
the house when built 1955

I get about 6 years out of my tanks. They rust out on the bottom.
The Whirlpool that just failed, had a broken weld joint at the cold
water inlet. I'm on a municipal water system.