Toys And The Water Dish

Hi, I'm new here and have a strange problem with one of my cats. Not a big problem--more a nuisance.
I have several of the fur-covered mice that you fill with catnip. Well...he has begun dunking them in the water dish!! They become soaked and then he ends up with them on the bed, sofa/chairs, etc. --- and, of course, the water becomes greenish and has to be replaced.
I don't want to get rid of the toys, as I have 17 other cats and kittens...and these mice are their favorite toys.
I have been around and caring for cats for over 50 years and pretty much have dealt with almost every attitude and problem imaginable....but this really blows my mind. It's really comical to watch this huge 14 pound cat go through this process -- I just wish the results weren't a problem.
You know...maybe he likes the taste of CATNIP TEA!
Has anyone else out there ever had one of their cats do this? This is what I am really curious about---why is he doing it?

Yep I ended up tossing out all the mice and getting ping pong balls. The cats love to chase those and they float!

Hi Hissy-Really! Your cats did it too!!! Isn't it something? They carry these mice all over the house-throw them up in the air, and chase them--fight and growl over them---just mainly have a ball. It's just this one guy that does it and I can't figure why----that's what fascinates me----and frustrates me.

I have an 8-year-old male kitty who has dunked his toys in the water dish ever since he was a baby. Mice toys, balls, crinkle toys, catnip toys...he will even drag a fishing pole toy to the water dish and throw it in. My only interpretation of this is that somehow throwing the toy in the water signals that he has "killed" it. Not much help, I know, but at least you know there are others out there...

Amanda