There are some things that were not mentioned.
1) Obviously you're talking about traditional spinning platter drives, and not SSDs.
2) The complete drive needs to be overwritten to be sure all data has gone. The safest way to do that is to use an ATA secure erase command. This will overwrite all the sectors marked as bad. DBAN is good, but it will not overwrite sectors marked as bad. (The risk from this is small.)