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My cat drinks a lot of water. Should I be worried?

My cat drinks a lot of water. Should I be worried?

Written by Mara | November 27, 2025

If your cat suddenly starts drinking more than usual, you should take it seriously. Cats are naturally careful drinkers, so a clear increase stands out. And rightly so, because it can point to an underlying problem. This blog explains when drinking a lot is a concern, what the possible causes are, and what you as an owner can do.

When does a cat drink too much?

On average, a healthy cat drinks about 40 to 60 ml of water per kilogram of body weight per day. However, many cats get part of their fluids from wet food, which often means they drink less.

Signs your cat is truly drinking a lot:

You need to refill the water bowl more often than usual
Your cat seeks extra drinking spots (taps, plant pots, shower floor)
A much fuller litter tray due to more urination
Wet patches around the bowl because your cat drinks more eagerly

Do you notice these changes? That is always a reason to be alert.

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Possible causes of excessive drinking

Drinking a lot, and often urinating a lot as well, can be the result of various conditions. This is also called polyuria/polydipsia (PU/PD). There are several health reasons why a cat may start to drink and urinate more:

Kidney problems (especially in older cats)
Diabetes
Thyroid problems (hyperthyroidism)
Urinary tract infection
Medication effects (for example prednisolone)
Food high in salt or a switch to mainly dry food

Less well-known causes of PU/PD include:

Hypercalcaemia (too much calcium in the blood): a rarer but important cause. Cats may drink more, urinate more, eat less and sometimes feel nauseous.
Behavioural drinking: some cats drink more out of boredom, stress or because they find a new water source interesting (fountain, tap). This is less often the reason and should only be considered once medical causes have been ruled out.

When should you be concerned?

Short answer: if your cat clearly drinks more than normal, you should take it seriously. A change in drinking behaviour is often one of the first signs in cats that something is wrong. Even if your cat otherwise eats, plays or behaves normally, there may still be an underlying problem.

What can you do yourself?

There are a few things you can already do before visiting your vet.

Observe and note

How much does your cat drink per day, roughly?
Is there more urine in the litter tray?
Are there other changes (weight loss, big appetite, lethargy)?

This information is very valuable for the vet.

Check the food

Has anything changed in the diet recently?
Does your cat mainly eat dry food?

Wet food can help improve fluid balance a little, but it does not solve medical causes.

Keep offering water

Never leave your cat without water, even if you think it is drinking “too much”. If there is a medical reason, your cat will dehydrate if you take the water away.

When should you see the vet?

With any visibly increased drinking, a vet visit is advisable. With a simple blood and urine test, kidney problems, diabetes and other conditions can be ruled out or detected quickly. The earlier you act, the better the outlook.

Drinking a lot is not normal for cats. It does not mean it is immediately something serious, but it is a sign that deserves attention.

Do you still have questions about your cat’s drinking behaviour? Then contact us at veterinarian@vetsend.co.uk.

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Chronic kidney failure in cats and dogs

Chronic kidney failure is a common condition in older cats. As the name suggests, chronic kidney failure means that the kidneys have not been functioning properly for a long time. Unfortunately, owners don't always catch the early signs of this condition, and as a result it is often diagnosed at a late stage. If you notice that your ageing cat is becoming slow, has a reduced appetite and a dull coat, is losing weight or drinking and urinating more than he used to, getting him checked over by your veterinarian is a good idea. It is possible that his kidney function is deteriorating.

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About the author

Mara van Brussel-Broere, Veterinarian at Vetsend

Graduated as a companion animal veterinarian from Utrecht University, she uses her practical experience to advise customers and share knowledge at Vetsend. She finds it important to provide pet owners with clear information about health and wellbeing.