When a thirsty cat is thirsty, any water will do.
That cat will get salmonella…It’s cute, but it’s a shame how dumb pet owners can be. I’m worried about children handling the turtle, and then putting their hands in their mouths due to dumb animal handling and parenting. People need to get educated. :\
You only get salmonella in the water if it is introduced it into the water. The turtle may have salmonella on its shell when you first get it from a fleemarket because it was raised in an area where adult turtles are given raw chicken (BAD IDEA!!!). The optimal conditions for turtles are not the same for salmonella. Over a few weeks with regular water changes the salmonella will be gone. However I still would not recommend having your cat drink exclusively from the turtle tank.