How Much Water Should a Cat Drink a Day? Amounts by Weight

How much water should a cat drink? Less than most of us expect from the bowl, and more than most cats manage on dry food. The useful number is total water, from food and drinking combined. We’ll give you the vet rule of thumb, a chart by weight, and a worked example using our cat food calculator to show how much the food itself supplies.

How much water does a cat need a day?

Cornell’s Feline Health Center says a cat needs about 4 ounces of water for every 5 pounds of lean body weight each day. Use her ideal weight, not her current weight, if she’s carrying extra. Here’s what that looks like:

Lean body weight	Total water per day	Too much (over 100 mL/kg)
6 lb (2.7 kg)	About 145 mL (5 oz)	Over 270 mL
8 lb (3.6 kg)	About 190 mL (6.5 oz)	Over 360 mL
10 lb (4.5 kg)	About 240 mL (8 oz, 1 cup)	Over 450 mL
12 lb (5.4 kg)	About 285 mL (9.5 oz)	Over 540 mL
15 lb (6.8 kg)	About 355 mL (12 oz)	Over 680 mL

Treat these as a ballpark. A 2025 review of 32 studies found healthy cats took in anywhere from 23 to 51 mL per kg a day in total, a bit under the National Research Council’s reference figure of 50 to 60. So a healthy cat drinking less than the chart isn’t automatically dehydrated. One caveat on that review: some of its authors have links to the pet food industry.

How much of that comes from food?

This is why the question is so confusing. Merck lists canned cat food at 60% to over 87% moisture and dry food at just 3% to 11%. A wet-fed cat can get most of its water from dinner. A dry-fed cat has to drink nearly all of it.

The review backs this up: cats on dry food took in less water overall and had more concentrated urine.

Worked example: a 10 lb cat on wet, dry or mixed food

Say you have a 10 lb, neutered adult cat at a healthy weight. In the cat food calculator, choose “Adult, spayed/neutered”. It suggests about 260 kcal a day. Using the default food values (90 kcal per can, 400 kcal per cup of dry):

Diet	Calculator says	Water from food (approx.)	Left to drink to reach ~240 mL
All wet	2⅞ cans	About 190 mL (2.9 cans × 85 g at 78% moisture)	About 50 mL
50% wet	1½ cans + ⅜ cup dry	About 100 mL	About 140 mL
All dry	⅝ cup dry (about 69 g)	About 7 mL	About 230 mL

We assumed 3 oz (85 g) cans and a label moisture of 78%. Check your own can, because moisture varies. The point stands either way: the dry-fed cat needs to drink almost a full cup, while the wet-fed cat might only lap a few tablespoons and still be fine.

For a cat that needs to slim down, the cat calorie calculator gives a lower target, and the wet food guide explains mixed feeding in more detail.

How can I get my cat to drink more water?

These tips come from Cornell, plus a few things we’ve found work at home:

• More bowls, in more places. Cornell suggests several easy-to-reach bowls, and in multi-cat homes, setting things up so one cat can’t block another from water.
• Try a wide, shallow bowl. Many cats seem to prefer not having their whiskers brush the sides. This one is our observation, not a study.
• Add water to food. A splash of water mixed into wet food is the easiest win.
• Switch some meals to wet. In the example above, going 50% wet lifts the water from food from about 7 mL to about 100 mL.
• A fountain, alongside a bowl. Preferences vary, so give her the choice.
• A little flavor. Cornell suggests a small amount of tuna water or low-sodium broth. Skip anything with onion or garlic.

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

International Cat Care puts the line at more than 100 mL per kg a day. To measure it, fill the bowl to the brim with a known amount and measure what’s left 24 hours later. If pets share bowls, you may need to keep them apart for the day, and a cat who drinks from taps or puddles outside will throw the number off.

Drinking more than usual can be an early sign of kidney disease, diabetes, an overactive thyroid or high calcium levels. Cats that drink more usually pee more too, so a fuller litter box can be the first clue. International Cat Care suggests taking a urine sample to the vet if you can.

What are the signs of dehydration in cats?

Cornell lists lethargy, weakness, poor appetite, dry or tacky gums, sunken eyes and skin that stays tented when you gently lift it at the shoulders. Older cats can have less elastic skin even when they’re well hydrated, so the skin test is less reliable in seniors.

If you also have a dog, our post on how much water a dog should drink and the dog water intake calculator cover the other side of the house.

When to call your vet

Call your vet if:

• Your cat is drinking noticeably more than usual, or more than 100 mL per kg a day.
• She has signs of dehydration, especially with vomiting or diarrhea.
• She’s eating less and losing weight, or drinking more and losing weight.
• A dry-fed cat seems to have stopped drinking.
• She’s peeing much more than normal, or having accidents outside the box.

Go the same day if a male cat is straining in the litter box with little or no urine. A blocked bladder is an emergency.