---
title: "Why Is My Cat Drinking So Much Water UK?"
description: "UK guide — increased thirst in cats often signals kidney disease, diabetes, or hyperthyroidism. Know normal intake, measurement tips."
url: "https://pethealth.org.uk/health/why-is-my-cat-drinking-so-much-water-uk"
canonical: "https://pethealth.org.uk/health/why-is-my-cat-drinking-so-much-water-uk"
date_published: "2026-06-25"
date_modified: "2026-06-25"
source: "PETHEALTH+"
---

# Why Is My Cat Drinking So Much Water UK?

**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.

## How much is too much?

According to International Cat Care, average intake is about **50 ml per kg per day** — variable with diet.

| Cat weight | Approximate normal daily intake |
|------------|--------------------------------|
| 3 kg | ~150 ml |
| 4 kg | ~200 ml |
| 5 kg | ~250 ml |

**Wet food diets** supply much fluid — bowl drinking may look low. **Dry food only** increases visible drinking — but **change from your cat's normal** matters more than a textbook figure.

### How to measure at home

1. Fill bowl to a marked level each morning
2. Refill only when empty and **note volume added** for 2–3 days
3. Tell your vet the totals and diet type (wet vs dry)

## Common causes in UK cats

### Chronic kidney disease (CKD)

Very common in cats **over 10**. Damaged kidneys lose concentrating ability — cats drink more to compensate.

Other signs: [weight loss](/health/cat-weight-loss), poor coat, reduced appetite, vomiting. See [Kidney disease in cats](/health/kidney-disease-in-cats).

### Diabetes mellitus

Middle-aged and older **overweight cats** are at risk. Excess thirst with **increased appetite and weight loss** is classic.

Untreated diabetes can become **diabetic ketoacidosis** — emergency with vomiting and collapse.

### Hyperthyroidism

Overactive thyroid in senior cats increases metabolism — drinking, hunger, and activity rise; weight may still drop.

See [Hyperthyroidism in cats](/health/hyperthyroidism-in-cats).

### Urinary tract disease

[FLUTD](/health/flutd-cats-uk) and infection sometimes alter drinking — often with straining or accidents.

### Liver disease and other conditions

Less common but included in vet work-up.

### Medication

Steroids and some drugs increase thirst — expected side effect; discuss with prescribing vet.

## When drinking increases without other signs

Early CKD and hyperthyroidism may show **only polydipsia** initially. Do not wait for collapse — **senior cat checks** from age 7–10 catch these earlier.

## Vet work-up

Expect:

- **Blood tests** — kidney values, glucose, thyroid hormone
- **Urinalysis** — concentration, glucose, infection
- **Blood pressure** — common with kidney and thyroid disease

Treatment depends on diagnosis — many conditions are **manageable** when caught early.

## What not to confuse

- **Hot weather** — mild increase possible; should normalise indoors with shade
- **New dry diet** — gradual increase; compare to baseline after diet change
- **Pregnancy or lactation** — queens need more fluid — vet supervised

Dogs with increased thirst differ — see [Dog drinking excessive water](/health/dog-drinking-excessive-water).

## Related guides

- [Kidney disease in cats](/health/kidney-disease-in-cats)
- [Diabetes in cats](/health/diabetes-in-cats)
- [Hyperthyroidism in cats](/health/hyperthyroidism-in-cats)
- [Senior pet care UK](/health/senior-pet-care-uk)

## FAQs

### 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.

## Sources

- [International Cat Care — Chronic kidney disease](https://icatcare.org/advice/chronic-kidney-disease/)
- [PDSA — Kidney disease in cats](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub)
- [Blue Cross — Hyperthyroidism in cats](https://www.bluecross.org.uk/pet-advice)

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Last modified: 2026-06-25