This is Dr. Christian. Welcome to JustAnswer.Typically a cat will start to get dehydrated after 1-2 days of not drinking. They can go 3-4 days without eating and do fairly well. Dehydration is the most immediate concern. At this point she has got to be very dehydrated and that will worsen the situation After 3-4 days of not drinking it can become life threatening. It's best to have her rechecked immediately rather than waiting longer. At the very least, some fluids can be given to keep her hydrated. If you have more questions please let me know.