Why is my cat suddenly drinking a lot more water?

A sustained increase in drinking is one of the most informative signals a cat can give. As kidneys lose their ability to concentrate urine, cats start drinking and urinating more to compensate. Increased thirst also shows up early with diabetes and an overactive thyroid. Cornell notes that chronic kidney disease affects up to 40 percent of cats over 10 and 80 percent over 15, and earlier diagnosis reliably means a better outcome. A real change (not a hot day, not a couple of busy laps) is worth a same-week vet visit, with blood work and a urinalysis. The earlier this gets caught, the more options there are.

When to call a vet: don’t wait this one out: book a vet visit when you notice the change, not after weeks of watching.