More adventures in doggie In's & Outs

Yesterday, we followed the output of the old lady doggie.  Her urinalysis was still too diluted.  Today, we start to monitor her input.  Vet wants to know how much water she will drink a day.  This becomes an issue when there are 2 dogs and 2 waterbowls in the house.  Good thing is that the other dog is pretty smart and a lot less OCD about his food and water.  Here I sit, next to the water bowl that is filled with a carefully measured amount of water.  I've already had to holler at the smart dog once, for drinking from the bowl.  He thinks I'm crazy (and he's right) but he'll figure it out.  If you have any suggestions how to best monitor this...  please let me know.  Vet wants average daily water ingestion per day, over several days.  I'll keep you posted.