Cat Health
Why Is My Cat Drinking So Much Water UK?
Quick answer
**Sudden or gradual increase in drinking often means illness in cats** — especially [kidney disease](/health/kidney-disease-in-cats), [diabetes](/health/diabetes-in-cats), or [hyperthyroidism](/health/hyperthyroidism-in-cats). Cats hide disease well; polydipsia is an early clue. Book vet **blood tests and urinalysis** if your cat's water bowl empties faster than usual for more than a few days.
Key takeaways
- Most cats drink roughly 50 ml per kg bodyweight daily — about 200–250 ml for a 4–5 kg cat. Drinking noticeably more than usual for several days warrants vet blood and urine tests.
- Wet food provides much of daily fluid needs. Cats on dry kibble only often drink more from the bowl — but a sudden increase still needs investigation, not dismissal as normal for dry food.
The full picture
Causes, home monitoring, treatment options and the exact signs that mean call your vet — in the complete guide.
Frequently Asked Questions
- Why is my cat drinking so much water?
- Increased thirst (polydipsia) commonly indicates chronic kidney disease, diabetes mellitus, or hyperthyroidism in UK cats — especially over eight years old. Less common causes include urinary tract infection, liver disease, and certain medications.
- How much water should a cat drink per day?
- Most cats drink roughly 50 ml per kg bodyweight daily — about 200–250 ml for a 4–5 kg cat. Drinking noticeably more than usual for several days warrants vet blood and urine tests.
- Is wet food enough water for cats?
- Wet food provides much of daily fluid needs. Cats on dry kibble only often drink more from the bowl — but a sudden increase still needs investigation, not dismissal as normal for dry food.
- When is increased thirst an emergency?
- Extreme lethargy, vomiting, collapse, or not eating with heavy drinking needs same-day care. Diabetic cats can develop ketoacidosis — an emergency.
Reviewed 2026-06-25 against UK veterinary guidance · Information only — not a substitute for seeing your vet.