Cast iron tubs are the most durable type of bathtub that you can by. The iron is going to provide immense strength against shocks and pressure, and you won’t have to ever worry about it cracking. A common issue with cast iron is rust, but with these models coated with enamel, it’s not something you’ll have to worry about. They also don't stain very easily. Due to these features, there is no reason that a cast iron tub won’t last for decades, and it’s likely that once you have it installed, you’ll never have to think about getting a new bathtub again.