How Much Water Should a Cat Drink? Hydration Tips

Short answer: the Cornell Feline Health Center says cats need about 4 ounces of water per 5 pounds of lean body weight per day, so a 10-pound (4.5 kg) cat needs roughly one cup (about 240 ml) in total. That total includes the water in food. Cats on wet food drink less from the bowl, cats on dry food drink more, and a sudden change in drinking is worth a call to your vet.

How much water does a cat need?

Cornell's rule of thumb is simple: 4 ounces per 5 pounds of lean body weight each day. For a 10-pound cat that is about 8 ounces, or one cup. Smaller and larger cats scale up or down from there. If you are unsure whether your cat is at a healthy weight, our guide to how much to feed a cat explains portions and body condition.

Wet food, dry food and water

Wet food can be up to 80% water, according to Cornell, so cats that eat it often drink less from their bowl. Cats fed dry food get more of their water by drinking. Neither is wrong, but a cat on dry food needs easy access to fresh water, and it is worth watching how much they actually drink. For a closer look at the trade-offs of each type of food, see Feeding Your Wegie: Wet Food vs Dry Food for Optimal Health.

Why cats may not drink enough

Cornell groups the causes of low water balance into two types.

• Increased water loss: chronic kidney disease, diabetes, vomiting, diarrhoea, hyperthyroidism, and some heart-disease diuretics.
• Decreased intake: weakness, low appetite, dental pain, or no access to water, for example an outdoor cat with no bowl nearby or conflict with other cats around the water.

That is why a change in drinking can be a clue to something else. Our guides to chronic kidney disease in cats, dental disease and vomiting cover related signs.

Signs of dehydration

• lethargy and weakness;
• poor appetite;
• dry mucous membranes, such as dry or tacky gums;
• in severe cases, sunken eyes.

Cornell also describes a skin test: gently lift the skin over the shoulders and see how quickly it returns flat. In a hydrated cat it springs back almost immediately; in a dehydrated cat it takes longer and may stay "tented". Older cats can have reduced skin elasticity even when well hydrated, so the test is less reliable for them. Treat it as a hint, not a diagnosis.

If you suspect dehydration, contact a vet promptly. Vets can treat it with fluids given into a vein or under the skin, and finding the underlying cause is just as important.

Ways to encourage drinking

These tips come from Cornell's hydration advice:

• Keep fresh water in easy-to-reach spots around the home.
• Make sure other pets cannot block your cat from the bowl.
• Try a water fountain. Cats vary in whether they like them, so watch what your cat does.
• Feed wet food, or add a little water to meals.
• Flavour the water with a small amount of tuna water from a can or low-sodium chicken broth.

Placement matters too. The AAFP and ISFM environmental guidelines recommend offering at least two options for each key resource, including water, and keeping resources in separate places. In a multi-cat home, that makes it harder for one cat to guard the water. See our guide to introducing a new cat for how to set up a shared home.

Water and the litter tray

A cat that suddenly drinks and urinates much more than usual, or that strains in the litter tray, needs a vet visit. Our guides on straining to pee and not using the litter box explain what to look for.

Quick checklist

• Aim for about 4 ounces of water per 5 pounds of lean body weight per day, from food and drinking together.
• Wet food adds water; dry food means more drinking.
• Offer fresh water in more than one place, away from the food and litter.
• Dry gums, lethargy or poor appetite mean a vet call.
• A big change in drinking is a reason for a check-up, even if your cat seems well.

Good drinking habits are one part of routine care. Raise any changes at your yearly vet check-up.

Keep reading

• How much should you feed a cat?
• Feeding Your Wegie: Wet Food vs Dry Food for Optimal Health
• Chronic kidney disease in cats: signs and care
• Essential Nutrients for Ragdoll Cats: Supporting Their Growth and Health
• Managing Your Russian Blue's Weight: Feeding Tips and Portion Control
• Cat straining to pee: urinary problems

Sources

• Cornell Feline Health Center: Hydration
• VCA Animal Hospitals: Feline environmental needs guidelines (AAFP/ISFM)