I thought the water heater rods were magnesium? They might be aluminum.
Seems like a funny recommendation to not use hot water from the tank because of an aluminum rod, but to use an aluminum pot on the stove?
The simple answer is to use the cold water tap and plan around it needing to get to a boil. Use that time to go grab your other stuff out of whatever spaces you store it in, start getting your fermenter ready, things like that.
Definitely like the idea of having a water filter as well and not just using the tap, but that's another subject.