If your cat is drinking more water than usual, the cause may be related to diet, warm weather, or activity, but it can also be linked to medical concerns such as hyperthyroidism, chronic kidney disease, or diabetes mellitus. Cat veterinarians can evaluate changes in water intake, litter box habits, weight, appetite, and behavior to determine whether testing such as bloodwork and urinalysis is needed.
Quick Answer: What Does It Mean When My Cat Drinks a Lot of Water?
Cats are low-thirst animals by nature. They evolved eating prey with high moisture content, so a healthy cat on wet food may barely touch a water bowl. When a cat starts drinking noticeably more, it’s one of the clearest early signals that something is off. The most common causes are hyperthyroidism, chronic kidney disease, and diabetes mellitus, all of which are manageable when caught early.
What Normal Water Intake Looks Like for Cats
A cat eating dry food may need closer to 7 to 9 ounces of total water per 10 pounds of body weight per day, though the exact amount depends on diet, activity level, environment, and health. A cat on wet food may drink much less because the food itself is 70 to 80 percent moisture.
If your cat recently switched to dry food or a drier diet, increased water intake is expected. The same goes for hot weather or more active play. The concern is when the change is noticeable, sustained, and doesn’t match any dietary or environmental shift.
Behavioral clues that thirst has increased:
- Drinking from faucets, cups, or sources your cat previously ignored
- Emptying the water bowl completely within a day
- Increased urination, including larger clumps in the litter box
- Accidents outside the litter box
The Part Most Guides Don’t Say Clearly Enough
Cats are exceptional at hiding illness. Unlike dogs, who often show obvious behavioral changes when something is wrong, cats frequently appear completely normal until a condition has progressed significantly. Increased water intake is one of the few early behavioral changes that owners can actually notice at home.
That makes polydipsia in cats especially important to take seriously. By the time a cat shows multiple symptoms, you may already be dealing with a later-stage condition. A noticeable change in drinking habits that lasts more than a few days, especially with changes in appetite, weight, energy, or litter box habits, is worth a call to your vet.
Medical Causes of Excessive Thirst in Cats
Hyperthyroidism
The most common endocrine disorder in cats over 10 years old. An overactive thyroid raises overall metabolic activity and can affect several organs, including the heart and kidneys. Increased thirst and urination, weight loss despite a strong appetite, and hyperactivity are the classic combination.
Chronic Kidney Disease (CKD)
CKD is one of the most common diseases in older cats and a leading cause of illness and mortality in geriatric cats. Damaged kidneys can’t concentrate urine, so the cat passes large amounts of dilute urine and compensates by drinking more. It often progresses silently, which is why many veterinarians recommend routine screening, including bloodwork and urinalysis, for cats around age seven and older.
Diabetes Mellitus
Diabetes mellitus is common in both dogs and cats, and the mechanism is similar: excess blood glucose passes into the urine and causes the body to lose more water. Cats with diabetes often show increased thirst and urination, weight loss despite a good appetite, and, in advanced cases, may develop hindlimb weakness or a plantigrade stance from diabetic neuropathy.
Other Causes to Rule Out
- Urinary tract infection (though more common in dogs, it does occur in cats)
- Liver disease
- Hypercalcemia
- Certain medications, including corticosteroids
When to Call the Vet
Schedule an appointment promptly if your cat’s increased drinking is accompanied by:
- Weight loss without a diet change
- Vomiting or reduced appetite
- Lethargy or withdrawal from normal routines
- Changes in litter box habits, including larger or more frequent urination
A urinalysis and blood panel can help identify many common causes or point your veterinarian toward the next diagnostic step. The sooner these tests happen, the sooner your veterinarian can identify the likely cause and discuss appropriate treatment or management options. Cats need a different diagnostic approach than dogs, so booking a visit with a veterinarian who has feline experience can make a real difference in getting to the right answer quickly.
If your dog shows it too, the causes overlap in some areas but differ enough to be worth a separate read.
Final Thoughts on Why Is My Cat Drinking More Water Than Usual?
Increased thirst in cats should not be ignored, especially when it is noticeable, sustained, or paired with other changes. Given how well cats mask illness, a change in water intake is often the first useful signal owners have that something needs attention. The good news is that hyperthyroidism, early kidney disease, and feline diabetes can often be treated or managed, especially when they are diagnosed before multiple symptoms develop. The Vet Set is at 577 Henry Street in Carroll Gardens. Call us at 917-909-1733 or schedule an appointment to get a clear answer.