If the hands is num and when i touch the water and its hurts.what causes that.?

Nerves or vessels.: Usually numbness in a part of your body happens because the nerves are damaged directly, or the vessels that supply the nerves are blocked or damaged. You should talk with your doctor about finding a cause. They should examine all the way up to your neck as well, because numbness in the hand can start at your neck. Please get this checked out and best of luck!