Why does the car's water tank rust? How to deal with it?

Nowadays, cars must be added with special antifreeze, and clean water is not allowed. If the water tank is rusty, you can clean it with something like a water tank treasure. Nowadays, the calorific value of automobile engines is generally relatively large. If water is used as coolant, it is easy to rust and boil. The use of antifreeze not only has a high boiling point, but also protects the water tank and cooling system of the car.