There's a lot of flood-damaged computers out there right now, and a lot of people hoping their data can be recovered. That's likely to require specialist skills, but you can make sure that the process has the maximum chance of working by not trying to dry the drives beforehand.
That might sound counter-intuitive, but data recovery specialist Kroll Ontrack explains in a blog post on its site that attempts to get rid of excess water often make matters worse, and your best bet is not to do anything much:
Although it sounds paradoxical, keeping a hard drive wet aids data recovery. We therefore recommend putting the hard disk in a sealed container or plastic bag to prevent it drying out until professional engineers can dry the platters and other components in a sterile environment.
By the same token, you shouldn't try and power up a water-damaged drive either. Hit the link for more tips on successful drive recovery.
Top Four Data Loss Prevention Tips [Kroll Ontrack]