how much water would cause damage?

It's hard to say. I would let that area dry out 100% before plugging it in, for obvious reasons. I don't think something like that would cause any damage though.

There's a slim chance rain can do some major damage as the majority of the surface area of the iPad is the screen and the water can't get in this way. If it's a torrential downpour though and you're outside using your iPad, it's likely water will enter through the headphone port and charging area, etc.

 

You're probably fine.

 

I think that it will handle it I got some of my electronic stuff pretty wet during different occasions and nothing ever got broken.. But i would let it dry before using it!

 

This post has made me speechless.I can't say anything after this.