I am in the middle of replacing a drain in the concrete floor of my basement. I'm replacing it because the current drain is terribly rusted, and was quite crooked in terms of not being flush with the floor. I'm getting ready to seal the concrete and figured I might as well put in a nicer drain. Now that I've broken out the concrete around it, I can see that it's a St. Louis style drain, and I'm assuming it's cast iron.
I had been thinking "Why on Earth do they make these water-channeling fixtures out of cast iron when cast iron rusts so easily? I thought maybe that was just how it was done in the old days, but that now you wouldn't see iron being used for plumbing. However, now I'm looking for fixtures to replace the rusted drain with, and I notice a lot of these are made of ductile iron. I know that ductile iron is a different alloy, but does it not rust? I'm looking to install something that won't rust, so I need to figure out if ductile iron is off limits.