A comment, if I may.

On top of every tank-style water heater is a large heavy nut.
This nut is connected to a long, zinc rod.

It's not easy, as the tank must be off and completely drained, but replace this rod every 3 or 4 years, more often if your water is troublesome.

This will drastically mitigate tank-rot.

There are how-to guides all over the web explaining in detail.