I got a young leopard gecko a few days ago and he’s perfectly healthy, eats and drinks, but I just wanted to know if them screaming when water gets on the is normal. I sprayed water in his cage this morning and while I was doing that he wondered out of his hide, the moment water touched him he screamed and tried to escape.
Generally, a gecko screams when it is frightened or startled. Probably it wasn't expecting the stream of water and was shocked/surprised either by the splash of water itself, or by water that was at an uncomfortable temperature.
You should not use water that is too cold, nor water that is boiling-hot. Room temperature to slightly warm is the best - but please note that if your house is cool or cold in winter, you may want to use slightly warm rather than that of a room temperature.
It's most likely that no harm was done, but you should avoid scaring or startling your gecko as much as possible since it can be stressful to them.