Over the years I have amassed a stockpile of hard drives that contain data from previous computers I have owned. I have debated about what to do with the drives. I am concerned that even if I format them, then throw them away, my personal data could still be at risk of being recovered.
The good news is that I found out recently that the most secure way of erasing data from the hard drive is free and already built into the hard drive itself. Check out this article about Secure Erase to see what I mean.