How can I test fall detection on my Apple Watch?

I can guarantee you that if you have the fall detection on, Apple will most likely detect your hard falls. I don’t think its good to test the fall detection as Apple Watch cannot detect all falls and you may harm yourself.

• Let’s make sure you have fall detection on though, just in case:

1. Open the Watch app on your iPhone, then tap the My Watch tab. 
2. Tap Emergency SOS.
3. Turn Fall Detection on.

For more information: Use Fall Detection with Apple Watch - Apple Support

VillagerREV wrote:

I've fallen 3 times and the watch hasn't responded. How do I test it short of falling again?

There is no guaranty that the watch will detect all falls:

Apple Watch cannot detect all falls. Your watch might detect high-impact activity as a fall and trigger Fall Detection.

Use Fall Detection with Apple Watch - Apple Support

You may want to contact Apple and have the run diagnostics on your watch:

Genius Bar Reservation and Apple Support Options - Apple

If this is a serious issue for you (and it sounds as if it is), you might be better served by one of the devices whose only purpose is fall detection.

Well, you cannot test it, you can verify that it is on. To do that, open the watch app on your iPhone, scroll down to emergency SOS, then verify that fall detection is set to Always On.

My watch has occasionally triggered a fall detection alert when I was driving nails with a hammer.

I had it turned off, I realized, when I fell off my stairs (blame the cats) and landed face-first on my dining room floor. Thought I'd broken my ankle. I turned it on after that.