The side valve on my waterheater is leaking. A plumber came to the house today and said we need a new water heater and it would cost $800 which includes installation. I'm hesitant. This is the first time this happened, however, we've had the heater over 13 years. I think the valve just needs replacing.

Then just tell him to replace the valve if you wish.

But

A 13 year old water heater has seen better days. If I were you I would replace it.

And


I would get at least 2 estimates. I think 800.00 is high but that would depend upon where you live and cost of labor in that area.