is mishka still eating dry food? even after BG went down and still grazing on dry food, my cat still drank a good amount of water everyday, somedays more than others.
now like furbabies mention, mine is no longer drinking water either nor are any of the other cats and even the dog that got changed to all wet food, only drinks water after her walk now..
0ne-two pees in 12hrs isn't that much, all of our cats go that much or more too and its always more than a golfball size at a time.
i think if not eating dry and BG gets under 200 (250 is still high for some cats) you should see a regular decrease in water intake, unless of course your kitty just loves water (we have one that will drink from faucet if we let him wether he is thirsty or not because he just loves to do so).
As for measuring how much your cat is drinking, measuring water you put into bowl at a particular time everyday and emptying what's left in bowl back into measuring cup at same time everyday, would be a way to figure it out.