Is it possible to built a basement in North Texas with a bathroom in it?

Question

If not would you have to go to a place where they make and install basements for tornados?and it's made out of steel.

Answer 1

Plenty of basements have been built with bathrooms in them, and it has no relation on where you are located.  You certainly can.  However, you might well have to install a sewage/sump pump system to pump the drain/waste vertical before it can be drained naturally via gravity.