Don’t let this happen to your water heater. Drain water heaters once a year to remove accumulated sediment and mineral debris. Over time, sediment builds up at the bottom of the heater which will rust through and destroy the tank. Always follow the manufacturer’s instructions for draining a water heater.
Here is a little more on rust:
Rust is the common name for iron oxide. Iron oxide is common because iron combines readily with oxygen. So readily, in fact, that pure iron rarely occurs in nature.
Iron (or steel) rusting is an example of corrosion: an electro-chemical process involving an anode (a piece of metal that readily gives up electrons), an electrolyte (a liquid that helps electrons move) and a cathode (a piece of metal that readily accepts electrons).
When metal rusts, the electrolyte helps provide oxygen to the anode. As oxygen combines with the metal, electrons are liberated. When they flow through the electrolyte to the cathode, the metal of the anode disappears, swept away by the electrical flow or converted into a form like rust.
Make sure to clear out your water heater regularly. Pictured here is a rusted water heater bottom.
https://alllosangelespaintingcompany.com/2022/07/water-heater-flushing/