How much water should a dog drink a day?

It varies a lot with size, diet, weather and activity, which is why the change matters more than the number. Measuring your dog’s intake over two or three days gives your vet something concrete to work from.

Should I limit my dog’s water if they are drinking too much?

No. If a medical condition is driving the thirst, restricting water can cause harm quickly. Always leave water available and take the drinking itself to your vet.

What illnesses cause increased thirst in dogs?

Diabetes, kidney disease, Cushing’s disease and womb infection in unspayed females are among the recognised causes, along with some medications. Several are much easier to manage when caught early.

My dog drinks more and wees in the house — is that related?

Very often yes. Drinking more and urinating more usually go together, and accidents in a previously house-trained dog are worth mentioning specifically when you book.

My dog is drinking a lot of water

A dog drinking noticeably more than usual, for more than a day or two, is one of the most useful early signals owners can spot. It is often the first outward sign of conditions that are far easier to manage when caught early — which is exactly why it is worth a vet appointment rather than a water fountain.

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This is worth a call to your vet rather than waiting to see how it goes, particularly if it has lasted more than a day or your pet is otherwise off-colour.

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What counts as a lot

Hot weather, more exercise, a switch from wet food to dry, and some medications all increase thirst for entirely ordinary reasons. Those changes make sense in context and settle when the cause does.

What matters is a sustained increase with no obvious explanation, particularly when it comes with drinking in unusual places, emptying the bowl repeatedly, or needing to urinate more — including accidents overnight in a previously clean dog.

If you want a number to take to the vet, measure it. Put a known volume in the bowl each morning, measure what is left after 24 hours, and do that for two or three days. Your vet will find that far more useful than an impression.

What it can indicate

Increased thirst is a recognised early sign of several conditions, including diabetes, kidney disease, Cushing’s disease, and womb infection in unspayed females — the last of which is an emergency.

It also appears with some medications, notably steroids, and with liver problems and certain hormonal conditions. Several of these are entirely manageable when found early and much harder when found late.

That range is the reason this page does not offer a product. There is nothing you can buy that addresses the cause, and the value of noticing the change is entirely in what a vet does with it.

When to make the appointment

Book if the increase has lasted more than a couple of days without an obvious explanation. Sooner if your dog is also losing weight, eating more or less than usual, seeming tired, or has started having accidents indoors.

Immediately if your dog is an unspayed female with increased thirst, particularly a few weeks after a season, and especially with any discharge, lethargy or loss of appetite.

Never restrict a dog’s water to control the drinking. If a medical problem is causing thirst, taking water away can cause serious harm quickly.

What to bring

Your measured daily intake, your dog’s weight and any recent change in it, what they are eating, any medication, and when you first noticed the change.

A urine sample if your vet asks for one — a first-morning sample collected in a clean container tells them a great deal, and it is far easier to collect at home than in a car park.

Common questions

How much water should a dog drink a day?: It varies a lot with size, diet, weather and activity, which is why the change matters more than the number. Measuring your dog’s intake over two or three days gives your vet something concrete to work from.
Should I limit my dog’s water if they are drinking too much?: No. If a medical condition is driving the thirst, restricting water can cause harm quickly. Always leave water available and take the drinking itself to your vet.
What illnesses cause increased thirst in dogs?: Diabetes, kidney disease, Cushing’s disease and womb infection in unspayed females are among the recognised causes, along with some medications. Several are much easier to manage when caught early.
My dog drinks more and wees in the house — is that related?: Very often yes. Drinking more and urinating more usually go together, and accidents in a previously house-trained dog are worth mentioning specifically when you book.

Sources

Written against guidance published by UK veterinary and welfare organisations. Always confirm specifics with your own vet.

Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.