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Symptom guide

Why Is My Cat Drinking So Much Water? Causes and What to Do

Increased thirst in cats is often a sign of kidney disease, hyperthyroidism or diabetes. What's normal, what to watch for and when to see a vet.

Updated October 2026 · 6 min read · By the Hushku editorial team · 2 sources

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Short answer

Cats normally drink quite little, especially on wet food, so a cat that is drinking or peeing noticeably more needs a vet check. The most common causes are chronic kidney disease, hyperthyroidism and diabetes, all of which are more common in middle-aged and older cats and easier to manage when found early.

Key facts

  • Chronic kidney disease affects up to 40% of cats over 10 and 80% over 15.
  • Hyperthyroidism and diabetes are other common causes of increased thirst.
  • Never restrict water for a cat that's drinking more.
  • Senior cats benefit from twice-yearly blood and urine tests.

This guide is general information, not a diagnosis. If your pet seems unwell, or you're worried, call your vet.

Overview

Cats evolved to get much of their water from their prey, so many drink little, and cats on wet food may hardly visit the water bowl. That makes a change easy to spot: a cat that's often at the bowl, drinking from taps or the toilet, or producing bigger clumps in the litter tray is drinking more.

Increased thirst (polydipsia) and increased urination (polyuria) go together. They're among the earliest signs of several common diseases in older cats.

Go to a vet now if you see

  • Drinking a lot with vomiting, not eating or lethargy
  • Weakness, wobbliness or a sweet or unusual smell to the breath
  • Straining to pee or not peeing

Common causes

  1. 1. Chronic kidney disease

    Serious

    Very common in older cats: Cornell's Feline Health Center says it affects up to 40% of cats over 10 and 80% over 15. Damaged kidneys can't concentrate urine, so cats drink more.

  2. 2. Hyperthyroidism

    Serious

    An overactive thyroid causes weight loss despite a big appetite, thirst, restlessness and sometimes vomiting.

  3. 3. Diabetes

    Serious

    More common in overweight cats. Signs are thirst, peeing more and weight loss; early treatment can lead to remission in some cats.

  4. 4. A switch to dry food

    Usually mild

    Cats on dry food drink more than cats on wet food. A recent switch can explain a change.

  5. 5. Heat and medicines

    Usually mild

    Hot weather and some medicines, such as steroids, increase thirst.

  6. 6. Urinary tract infection and liver disease

    Needs a vet

    Less common causes your vet can test for.

What you can do at home

  • Never limit water; cats with kidney disease rely on drinking to stay hydrated.
  • Note how much your cat drinks over a day (measure the bowl), and any change in litter clumps.
  • Bring a fresh urine sample if your vet asks; non-absorbent litter makes this easier.

When to see a vet

  • Drinking or peeing noticeably more than usual
  • With weight loss or a change in appetite
  • Any cat over about 10 with increased thirst, even if it seems well

Prevention

  • Twice-yearly check-ups for senior cats, with blood and urine tests
  • Keep cats at a healthy weight to lower diabetes risk
  • Encourage drinking with wet food and fountains

Free tools for this

Sources

  1. Cornell Feline Health Center: Chronic kidney disease
  2. Cornell Feline Health Center: Hyperthyroidism in cats

We check guides against veterinary sources and update them when guidance changes. How we write and review.

Questions.

How much water should a cat drink?

Total water intake (food plus bowl) is roughly 40 to 60 ml per kg a day. A cat on wet food may drink very little from the bowl. A noticeable increase matters more than an exact number.

Is my old cat drinking more just because of age?

No. Increased thirst in an older cat is usually a sign of an illness such as kidney disease or hyperthyroidism, so it's worth testing.

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