Symptoms

Why is my cat drinking so much water?

Updated 2026-07-16 · Not a substitute for professional veterinary care

What counts as drinking too much

The signal that matters is a change from your cat's own normal. A cat that always drank little and now empties the bowl, hangs around taps, or drinks from unusual places has changed, and that change is the clue. Cats on dry food naturally drink more than cats on wet food, so compare each cat to itself, not to a chart.

The three common causes to know

• Kidney disease, very common in older cats. Failing kidneys cannot concentrate urine, so the cat drinks and urinates more to keep up.
• Diabetes, high blood sugar spills into the urine and pulls water with it, driving thirst. Often paired with a big appetite but weight loss.
• Overactive thyroid (hyperthyroidism), speeds up the whole body in older cats, raising thirst, appetite, and restlessness while weight drops.

All three are manageable when caught early, and all three often show increased thirst before anything else.

Why catching it early changes the outcome

These conditions develop quietly. By the time a cat looks obviously unwell, the disease is usually advanced. The rise in thirst is a rare early window. Noticing it, noting when it started, and bringing it to a vet can mean earlier treatment and a better outcome. This is exactly the kind of slow drift that is hard to judge from memory, which is why keeping a simple daily record helps.

When to see a vet

Book a vet visit if the increased thirst lasts more than a few days, or sooner if it comes with weight loss, a bigger or smaller appetite, more urination, vomiting, or low energy. Bring any notes on when the change began and what else you have noticed.