It is not the end of the world.
An owner drove through a water puddle fine:
Tesla in rain | Tesla
And the car wouldn't start the next day.
To get it working again, it would cost $9930.00.
Tesla didn't cover it because of water puddle.
However, car insurance did.
So, everything came out fine.
Tesla is still young and inexperience in the area of waterproof the car for road water.
However, there have been Tesla cars that survive through swimming water fine because Tesla does a pretty good job in designing it but not to the point of getting an ISO certification and not to the point for warranty purpose.
Hopefully, someday Tesla warranty will cover for road water.