How much water should dogs and cats drink each day?

A healthy dog drinks roughly 40 to 60 ml of water per kilogram of body weight a day. Cornell's Riney Canine Health Center gives that range and works it through for a 9 kg Beagle, which drinks about 360 to 540 ml. Veterinarians call a dog's drinking excessive once it goes above 100 ml per kilogram a day. Cats usually drink much less from a bowl than dogs, and how much they drink depends heavily on whether they eat wet or dry food.

What counts as a normal amount

The Merck Veterinary Manual puts the daily water need of most mammals at about 44 to 66 ml per kilogram in a comfortable temperature, and adds that healthy animals given enough water regulate their own intake well. That total includes the water in food, not only what comes from the bowl.

For dogs, using Cornell's 40 to 60 ml per kilogram:

Cats fall in a similar range per kilogram by the Merck figure, so a 4 kg cat needs somewhere around 175 to 265 ml a day. For a cat, that is total water from food and bowl combined, and a cat on canned food can take in much of it without drinking at all.

What changes the amount

Food. This is the biggest everyday factor. Merck gives the moisture content of canned pet foods as 60% to more than 87%, semimoist foods as 25% to 35%, and dry foods as 3% to 11%. Animals eating mainly canned food therefore drink less from the bowl than those on dry food. An 85 g pouch at 80% moisture holds about 68 ml of water; the same calories as kibble bring almost none.

Heat and exercise. Dogs cool themselves largely by panting, which loses water as vapor. Expect a dog to drink more on hot days and after long walks or play, and carry water on summer outings. Offer it in several smaller drinks after hard exercise rather than one long gulp.

Life stage. Nursing mothers drink far more than usual, because milk is mostly water. Puppies and kittens also need steady access to water once they are eating solid food.

Illness and medicines. Vomiting, diarrhea and fever all increase water loss. Veterinary Partner lists glucocorticoids (steroids such as prednisolone), phenobarbital and diuretics among the drugs that make animals drink and urinate more, and salt can contribute. If a pet starts one of these, the extra thirst is expected; water should not be restricted.

Drinking more than usual

A lasting increase in drinking, usually with more urine, is one of the earliest signs of several common diseases. The body is usually losing water through the kidneys first, and thirst follows to replace it. Veterinary Partner names the most common causes:

• In dogs: chronic kidney disease, Cushing's disease (hyperadrenocorticism) and diabetes mellitus.
• In cats: chronic kidney disease, diabetes mellitus and hyperthyroidism.

Cornell's list for dogs adds urinary tract infection, Addison's disease, pyometra (a uterine infection in unspayed females), liver disease, leptospirosis and some cancers, including lymphoma. Diagnosis usually starts with blood tests and a urinalysis, since how concentrated the urine is says a lot about where the problem lies.

Most owners do not measure water, but signs are easy to spot: the bowl empties faster, the dog asks to go out more often or has accidents, a cat's litter clumps get bigger or more numerous, or the animal starts drinking from toilets and puddles. To measure properly, put a known volume in the bowl each morning and measure what is left 24 hours later. Use one bowl only, keep other pets away from it for the test, and repeat for two or three days, since single days vary.

Signs of dehydration

• Dry or tacky gums instead of wet, slippery ones
• Skin at the back of the neck that is slow to fall back after being gently lifted (less reliable in old or very thin animals)
• Sunken-looking eyes
• Lethargy, weakness or loss of appetite
• Passing little urine

An animal that is dehydrated and still vomiting cannot catch up by drinking, and small, young or old animals lose ground fastest. These need a vet the same day. Fluids given by injection or drip work when drinking does not.

Helping a cat drink more

Cats with urinary stones or idiopathic cystitis are often advised to take in more water so that their urine is more dilute. Merck notes that cats often do not drink much and that several water sources encourage drinking. Beyond that, the evidence points more strongly at food than at gadgets.

In a 2026 study of cats fed all-dry, half-and-half and all-wet diets, cats drank the most water on dry food, but their total water intake, counting the water in food, was highest on wet food. Cats also drank more in the hours after meals than while fasting, whatever the diet.

Water fountains are widely recommended, but the evidence is thin. When healthy cats in their own homes were given water from a bowl and then a fountain, intake was slightly higher from the fountain, yet their urine was no more dilute. One cat refused to drink from the fountain at all. Cats differ, so a fountain can still be worth trying, placed next to an ordinary bowl rather than instead of it.

Practical steps, most likely to help first:

• Feed some or all of the diet as wet food, or add water to food the cat will accept.
• Put water in several places around the home, not only beside the food bowl.
• Refresh the water daily and wash bowls regularly.
• If a cat seems reluctant, try a different bowl shape or material.
• Offer a fountain as an extra option and watch whether the cat uses it.

When to call the vet

• Drinking clearly more or less than usual for more than a day or two without an obvious reason such as heat or a food change
• Increased thirst together with weight loss, a change in appetite, more urine or accidents in the house
• A pet that will not drink at all
• Vomiting or diarrhea that keeps going, especially in a puppy, kitten or older animal
• An unspayed female that is drinking more and is lethargic or has a discharge, which can mean pyometra and needs a vet urgently
• A cat straining in the litter box and passing little or no urine, which is an emergency

Sources

1. Canine polyuria and polydipsia (PU/PD). Riney Canine Health Center, Cornell University College of Veterinary Medicine, 2024.
2. Nutritional requirements of small animals. Merck Veterinary Manual.
3. Polyuria/polydipsia in dogs and cats. Carol Hershey, Veterinary Partner, 2022.
4. Water intake and consumption behavior of colony and privately-owned healthy domestic cats fed 100% dry, 50% dry and 50% wet, and 100% wet diets: a comparison of research and home environments. Journal of Animal Science, 2026.
5. Effect of water source on intake and urine concentration in healthy cats. Journal of Feline Medicine and Surgery, 2010.