Well, when I throw a dead body in the ocean I usually — uh no. Wait. I never do that. Really. Never. Nothing to see here. Just forget I said anything.
If it was me, I’d just throw the thing away. You already said it had died. If the drive had died to the point where you couldn’t use it in the PC, it’s likely to cost serious $$$ to revive it to the point where it could be imaged, and then THAT costs a whole lot of money. I.e. labor from guys who bill at $500+ an hour. Is there anything on it that anyone would spend multiple thousands of dollars to retrieve? Unlikely on 99.999% of home hard drives. Ask **Bayard **how much he bills out at, and how long it would take him to image and then retrieve anything useful from a hard drive. I bet it’s beyond anything the casual garbage surfer would be willing to undertake on a random hard drive.
If I felt the need to ensure that it was destroyed, I"d probably take pliers and just rip the circuit boards off and the power connectors. Barring that, a couple good whacks with a five pound sledgehammer would probably knock everything out of whack enough to render it even more inoperable.
I got rid of three older computers a few weeks ago, and it was too much hassle to even remove the drives to whack them.
Cordless drill, 3/8 bit, drill into each drive sideways, “chaw around” with the bit a little. Done. Takes about five seconds.
Although they feel sturdy and strong, HDDs are quite fragile. Sledge hammers and the like are fun but a light household hammer will work just fine, too, and the drill method is about like drilling a hole in a Home Depot 2x4 (== hard cheese).
My employer’s IT department took a whole bunch of old hard drives down to the machine shop and lined them up in a hydraulic ram (a machine for bending “sheet” metal up to 1/2" thick). The machine was big enough so that they could line up perhaps 20 hard drives in a row, and with a single stroke fold all of them 90 degrees.
At home, I just drill a hole through my old drives before putting them in a box full of old electronics for recycling. My old computers, sans hard drives, then get given away on craigslist.
Thermite is useful in these circumstances.
Physically disabling the drive like that should suffice in most real circumstances. Unless someone knows of particular valuable information on your drives they wouldn’t bother to try to recover data from a drive in such a state.
If the drive is only “mostly dead” but still spins up I’d be another vote for using DBAN. If it won’t spin up and you’re feeling paranoid then physically damaging the platters ought to do the trick as others have suggested.
The amount of effort you put in will be related to the value of the data on the drive. If you’ve stored tax returns or financial documents or that collection of interesting pictures that would be really embarrassing if made public then take a few minutes to sanitize the drive. You’d be amazed what people who should know better (including large companies) leave on old storage media that they discard without properly wiping.
R.e. magnets - I’ve told this story a few times before but we used to have a heavy-duty tape demagnetizer for erasing backup tapes. Someone brought in a notebook that they were disposing of and we decided to pull the drive and wipe it using the demagnetizer (which had specific instructions for erasing hard drives). Followed instructions (put disk on demag unit, spin it around several times, flip over, repeat - it makes a fearful noise as the changing magnetic field vibrates the disk platters). My co-worker put the now-erased drive back into the notebook, powered it up and…demag unit hadn’t done a damn thing. Notebook booted right up to the desktop and worked fine, zero issues.
I pulled out a DBAN CD, booted and overwrote the drive and we chucked it in the discard pile.
This!
Heats up the area around the hole, creates and spreads shrapnel, unbalances the platters for spinning, and is easy to do…if you have a drill.
If heat does damage, wouldn’t it be easiest just to bake the whole thing in the oven?
like a cake: a half hour at 450 degrees…
Would that warp the innards enough to make it unusable?
Seems easy…Does anybody know if it would work?
There are plastic parts of a hard drive, so I’d think that thirty minutes at 450 degrees would release some unpleasant odors.
I’ve discovered the best way to wipe out a hard-drive is to not have a back-up.
Likely it would disable the hard drive. OTOH, drilling/hammering doesn’t tend to release toxic fumes into your house.
I just dismantled 3 old hard drives this weekend after cleaning out the garage. I open them up and recover the two magnets. I love those powerful magnets and have a fist-sized clump of them, all stuck together.
I then took a pair of pliers and folded the platters into interesting shapes, including a conical form and the ever-popular “fortune cookie”.
You need to be very careful when doing this.
Some platters are glass, and appear to be metal without close inspection. Attempting to fold them will result in the expected explosion of glass shards.
While taking the drive apart and torching the surfaces of the disks will do the job, that’s really not necessary for ordinary folk.
Simply whacking the circuit board will do if the disk is going into the trash.
If you are recycling and are a tad paranoid, you might worry that someone might see your drive in a bin, decide to swap the board, etc. So whack it a few more times until the case is cracked open or bent.
To recover data from such a drive is very costly and the person doing the recovery would have to have a very good reason to attempt recovery.
A metal spike and a hammer can do amazing damage with little effort, as well.
I imagine just throwing the hard drive up in the air and letting it fall on a hard surface would also be a suitably low tech and effective technique.
I open them up and rescue the rare earth magnets first.
The 3.5" drives have magnets that come mounted on a nice little frame that has a couple of screw holes in it. Stick that to a handy stud in your workshop, and you can use it to hang heavy metal things.
I use mine to store a tape measure. But it will support a two pound hammer with ease.
And if it’s a small drive, the platters are likely glass. Give the drive a quick bout of hammer disease and shake to see if you hear shards.
I wouldn’t ever trust a simple “toss on the pavement” approach since a forensics company can open the drive in a clean room and remount the platters in a different enclosure. Pound enough so the platters are heavily deformed if not absolutely mangled. The aforementioned 2lb hammer is enough for me to be satisfied.
Seriously people, if you don’t need to save the drive itself there is no reason to bother with software erasure. Those programs can take days to run to completion. A spinning computer hard drive (non-SSD) is like a fine Swiss watch. One decent hit on the outside and it is completely un-fixable, unusable garbage.
Years ago on the old TechTV show The Screensavers Patrick Norton demonstrated how to destroy a hard drive. He had actually opened the enclosure first then hit it with a sledge hammer. Unbeknownst to him (and the crew) it was a newer, glass platter drive so shards went everywhere*!* Leo Laporte joked, "Jeez, that was the very first glass-platter drive we had and look what you did to it!" 
While it depends on the size and speed of the drive, a single pass wipe of a HDD less than 1TB should be done in less than a day. If it’s running into multiple days, something has probably gone amiss.
Holy crap, I just found it on YouTube! I mixed up who said what but it’s mostly as I remember.