Abnormal water intake in Cats

By Sophie Kininmonth · 6 Oct 2025 (updated 21 Jul 2026) ·6 min read

A cat parked at the water bowl is easy to miss, because most cats drink so quietly that any change is hard to spot. That change is worth catching. Increased drinking is one of the earliest signs of common feline health problems such as kidney disease, diabetes and an overactive thyroid, but it can also be something plain, like a switch to dry food or a run of hot weather. The good news is that thirst is measurable, and a day or two of watching usually tells you whether you are looking at a quirk or a warning. This guide covers what normal looks like, what counts as too much, and when to book the vet.

What normal water intake looks like

There is no single perfect number, because a cat's total water comes from both drinking and food. A commonly used guide is around 50 mL per kilogram of bodyweight per day from all sources, which works out to roughly 200 to 250 mL a day for a 4 to 5 kg cat.¹

In everyday practice, many healthy cats on wet food drink very little, because the food already supplies most of what they need. The useful red flag is not a fixed figure but a clear increase compared with that cat's usual pattern, especially when it comes with more urine in the litter tray.

When is it considered excessive?

Polydipsia, meaning excessive thirst, is often defined as water intake above about 45 mL/kg/day in cats, and many veterinary references treat more than 100 mL/kg/day as clearly abnormal.^{2, 3}

Measure what your cat drinks

If your cat is otherwise bright and stable, measuring intake over 24 to 48 hours gives your vet far more to work with than guesswork, and it separates "seems like more" from "is more".

Tip out and refill each water source with a measured amount.
Note any top-ups during the day.
After 24 hours, measure what is left and work out the difference.
With multiple pets, accurate measuring usually means separating them or using a single controlled water source.⁴

Do not restrict water to "test" thirst. If the drinking is compensating for illness, limiting water can make a cat much sicker.

Common reasons a cat drinks more

Increased thirst is usually tied to increased urine production. The body is losing more water, so the cat replaces it. Vets often group the two together as PU/PD: polyuria (more urine) and polydipsia (more drinking).

Diet and environment

Cats on dry food usually need to drink more, because kibble holds far less moisture than wet food. Wet diets can cover much, and sometimes nearly all, of a cat's daily water needs.¹ Warm weather, indoor heating, more activity and recent changes at home can also nudge intake up for a few days. These causes are often harmless, but they are still worth noting.

Medical causes that deserve prompt attention

Chronic kidney disease (CKD): early signs commonly include increased thirst and urination as the kidneys lose their ability to concentrate urine.⁵
Diabetes mellitus: excess glucose spills into the urine and drags water with it, driving bigger urine volumes and more thirst.
Hyperthyroidism: an overactive thyroid can raise thirst and urine output, often with weight loss despite a good appetite.
Urinary tract problems: cats with bladder inflammation may visit the tray more often, sometimes passing only small amounts. This can be mistaken for urinating more, so the full pattern matters.
Medication effects: corticosteroids and some diuretics can increase thirst and urination.
Less common causes: conditions affecting antidiuretic hormone (diabetes insipidus) can produce very dilute urine and marked drinking, though this is uncommon in cats.⁶

Why increased drinking matters

The drinking itself is rarely the harm. It is the signpost. A cat may be drinking more to keep pace with fluid losses from kidneys or hormones that are not behaving normally.

One common claim needs tightening: that excessive water intake causes dehydration. Drinking more is typically a response to dehydration risk, through increased urine losses. A cat can still become dehydrated, but that happens when it cannot keep up with those losses, or when illness cuts intake.

When to book the vet sooner

Arrange an appointment promptly if increased drinking comes with any of the following:

noticeably larger clumps in the litter tray, or more frequent urination
weight loss, reduced grooming, lethargy, vomiting, or reduced appetite
behaviour changes such as restlessness, yowling at night, or hiding
accidents outside the litter tray, straining, or blood in the urine

If your cat seems unwell, dehydrated, or cannot keep water down, treat it as urgent.

What your vet will check, and why

Most work-ups begin with history, an exam, and a few core tests that map hydration and organ function.

Urinalysis, including urine specific gravity, to see how well the kidneys are concentrating urine and whether glucose, protein, crystals or infection markers are present.⁷
Blood tests to assess kidney values, electrolytes, glucose and thyroid hormone, especially in older cats.
Blood pressure, often checked when kidney disease is suspected.
Imaging, ultrasound or X-ray, if the picture suggests kidney changes, stones or other structural issues.

In more complex PU/PD cases, vets may discuss specialised testing under veterinary supervision to separate uncommon causes, such as diabetes insipidus versus primary polydipsia.^{6, 3}

Supporting hydration safely at home

While you arrange assessment, or for cats that simply need encouragement to drink, small tweaks help without forcing anything.

Offer several water stations in quiet, easy-to-reach spots.
Try a wide, shallow bowl, since some cats avoid bowls that brush their whiskers.
Keep water fresh and bowls clean.
Consider a fountain if your cat prefers moving water.
Where suitable, increase wet food or add extra water to wet meals, and discuss diet changes with your vet if your cat has a medical condition.^{1, 8}

Two misconceptions worth clearing up

"Cats should only drink 50 to 60 mL a day."

Incorrect. Cats commonly need around 40 to 50 mL/kg/day of total water from food and drinking combined. For a 4 kg cat that is closer to 200 mL a day, though wet food may supply much of it.¹

"If my cat is drinking more, I should limit water."

Do not. Increased drinking is often compensatory, and restricting water can worsen dehydration and any underlying disease.

The bottom line

A cat's drinking habits are quiet data, gathered in small sips. When the pattern changes, measure intake over a day or two, note any shifts in urination, weight, appetite and energy, then take those observations to your vet. The cause is usually identifiable, and early treatment is generally gentler than late treatment.

References

Sophie Kininmonth

Dog lover and writer at My Pets Australia, sharing practical breed guides and care advice for Australian pet owners.