I had this problem with Lily after her spay surgery. Wash their veggies in water without wiping it off. Also, put a little 100% juice in their water. If it is a little sweet they will be more likely to drink it. With Lily what I did was mix equal parts of organic baby food (strawberry, pear, and apple flavor) with water. Once she drank that I diluted it to 1/3rd baby food, 2/3rds water. Once that was gone I diluted it again, then again and again until she was drinking plain water on her own.