Why Is My Cat Drinking So Much Water?

A cat that suddenly drinks a lot more water than usual often has a health problem, most commonly kidney disease, diabetes or an overactive thyroid. Hot weather or a switch to dry food can also raise thirst, so the pattern matters: a lasting increase should be checked by a vet.

How much water should a cat drink a day?

There is no single number, and intake changes from day to day. One veterinary clinic, Clarendon Animal Care, puts average intake at around 50 to 60 ml per kg of body weight per day. Vetster describes more than 100 ml per kg a day, about 1.5 oz per pound, as the mark of polydipsia. For a 10-pound cat, that works out to roughly 15 oz of water in a day.

Cats that eat canned food get much of their water from meals, so they may drink less from the bowl than cats on kibble. If you are thinking about diet, see our guide to wet cat food.

What causes a cat to drink more water than usual?

Possible cause	What is going on
Chronic kidney disease	The kidneys lose more water in urine, so the cat drinks to keep up
Diabetes	Extra sugar in the blood spills into the urine and pulls water with it
Hyperthyroidism	An overactive thyroid speeds up the body and increases thirst
Dry food diet	Less water comes from food, so more comes from the bowl
Heat or extra activity	A short-term rise that settles on its own
Vomiting or diarrhea	The cat drinks more to replace lost fluid
Some medicines	Steroids and diuretics can increase thirst

Veterinarian Dr. Pete Wedderburn, writing for Cats.com, explains that the thirst is often driven by the body making too much urine, which is why drinking more and peeing more usually show up together.

How do I know if my cat is drinking too much?

Look for a change from your cat’s own normal. Signs include refilling the bowl more often, more trips to the water, bigger or more frequent clumps in the litter box, and drinking from taps or other odd places.

International Cat Care suggests tracking intake over 24 hours if you are worried. Fill the bowl with a measured amount in the morning, then measure what is left the next morning. Choosing the right food and water bowls makes this easier.

Should I limit my cat’s water?

No. The Cornell Feline Health Center describes good hydration as essential for body functions such as temperature control, and says the most common causes of dehydration in cats are diseases that increase water loss. A thirsty cat is usually replacing water their body is losing, so keep fresh water available and have the cause checked.

When should you call the vet?

Book a visit if the extra drinking lasts more than a few days, or sooner if it comes with weight loss, appetite changes, more urination, vomiting or low energy. International Cat Care notes that vets usually take blood and urine samples to find the cause. Call the same day if your cat seems weak, stops eating or has dry gums or sunken eyes, which Cornell lists as signs of dehydration. Our guide to signs that your cat may be sick has more to watch for.

Frequently asked questions

Is it normal for an older cat to drink more water?

It is common, but it should not be written off as age. Increased thirst in a senior cat is a reason for a checkup.

Do cats drink more on dry food?

Yes. Kibble holds little moisture, so cats make up the difference at the water bowl.

My cat is drinking a lot but acting normal. Should I worry?

Yes, if it lasts. Thirst can be an early sign of illness before other symptoms appear, so a vet visit is still wise.