My ~4 year old cat (uncertain breed) has always had the habit of drinking out of water cups instead of his own bowl. Considering that we let him outdoors where he hunts rodents and birds, this makes said beverages unpleasant.
I allowed him to drink out of a near empty glass of water as a kitten, but I'd really like him to stop.
Every time I get water, I have to drink the entire container, lest my cat jump up on the table and stick his head inside. If the glass is empty, he'll come over to sniff it. He likes sniffing things in general, but that's a non-issue. He doesn't smell anything except tap water, but I almost exclusively drink that!
I tried putting things on top of cups. Coasters, screwdriver kits, books... Coasters are easy to fit and they discourage this behavior slightly, but I commonly see him push them away with his nose. Heavier items seem more effective, but also make it easier for me to knock the glass over, and I'd rather he not jump up on my table and desk at all.
The water bowl I want him to drink from is a used, plastic tin of Celebrations chocolates that we empty, clean and fill whenever it's running low. We take our cat for regular checkups and the vet never mentioned anything about him being dehydrated. When there are no water cups around, he'll drink out of the bowl, usually after taking a bite of food first.
How can I stop him stealing drinks?