I really don't know. I bought the house 8 years ago, and nobody said anything about the water heater being new when I bought it. So, I'd guess maybe 15 years old by now. Frank looked on it this afternoon to try to find a label saying when it was installed, but he says there's nothing like that on it.
What's worse - - It's located inside, in my laundry room, just about 6 inches from the door connecting that room to my living room. The living room has an unusually beautiful orange-blonde oak laminate floor that continues throughout almost all of the house. I've never seen laminate that is anywhere near matching that one. So, if the water heater dumps its water, I have to have the whole house re-floored.