Hot water tanks used to come with a 20 year guarantee. they now come with a 10 year guarantee.
Even in order to get the 10 years out of them they do require some maintainence.
annually drain them and flush out all the mineral rocks in the bottom, by hooking up a hose to the drain faucet.
Replace the Annode rod every year or so and even better is annualy. it is there to be eaten up by the electrolysis instead of the bottom of the tank. that rod is usually only about 10.00 and maybe 15 minutes to change it.
Bebop