Why Is My Cat Drinking So Much Water? Causes of Increased Thirst
Most owners notice only when the water bowl empties faster, or the litter box clumps get bigger. A sudden rise in thirst, called polydipsia, often goes hand in hand with more urine, and it is one of the most useful early signs that something is wrong. Many of the diseases behind it are manageable when found early.
How much is normal?
A common rule of thumb is that a cat needs about 2 to 4 ounces of water per 5 pounds of body weight per day, which includes the water in its food. Cats on wet food, which is about 75 percent water, drink little from the bowl, while those on dry food drink more. Hot weather, exercise and lactation increase intake. A cat that drinks more than about 4 ounces per 5 pounds from the bowl, or that has a clear change in habit, deserves a check. See wet vs dry cat food.
Measure at home
For two or three days, fill the bowl with a measured amount, such as in a measuring cup, and check what is left the next day. In multi-cat homes, this is hard, so look at litter box clumps and watch each cat. Note appetite, weight and energy. Take photos of the litter box if the urine volume looks very large. Share this with your vet.
Causes
- Chronic kidney disease. Failing kidneys cannot concentrate urine, so the cat urinates more and drinks more. See chronic kidney disease in cats.
- Diabetes mellitus. High blood sugar spills into urine, drawing water with it. See diabetes in cats.
- Hyperthyroidism. The overactive thyroid speeds up metabolism and affects the kidneys. See hyperthyroidism in cats.
- Urinary tract infection, or bladder disease. See urinary tract infection in cats.
- Liver disease.
- High calcium, from several causes.
- Pyometra, an infection of the uterus in unspayed females, which is an emergency. See when to spay or neuter a kitten.
- High blood pressure. See high blood pressure in cats.
- Medications, such as steroids and diuretics.
- Diet, such as high-salt foods or dry-only diets.
- Heat and dehydration.
- Behavioral causes, including boredom, though rare.
Related signs
Look for weight loss, increased appetite, vomiting, bad breath, lethargy, a poor coat and litter box accidents. See why is my cat peeing outside the litter box. A cat that has increased thirst and is vomiting and not eating may be seriously unwell.
What your vet will do
The vet will examine the cat, and run bloodwork, urine tests, a thyroid test and blood pressure. Urine concentration tells a lot. Imaging, such as ultrasound, may follow. See cat blood tests explained.
Treatment
It depends on the disease: special kidney diets and fluids, insulin and diet for diabetes, medication or radioactive iodine for the thyroid, antibiotics for infection and others. See how to give a cat subcutaneous fluids.
Do not restrict water
Water restriction can be dangerous. Provide fresh water in several places, and consider a fountain. See cat water fountains: worth it and how to get a cat to drink more water.
Outlook
Many causes are manageable, especially when found early. Regular checkups for older cats catch changes. See senior cat care guide.
Kidney disease and thirst
Chronic kidney disease is the leading cause in older cats. Early on, cats compensate by drinking and urinating more. By the time signs are obvious, a large share of kidney function may already be lost. Regular screening, including SDMA and urine tests, finds it earlier. Early treatment, with a kidney diet, hydration support and blood pressure control, can slow progression. See chronic kidney disease in cats.
Diabetes and hyperthyroidism
Cats with diabetes drink and urinate a lot, and often have a large appetite with weight loss. Cats with hyperthyroidism may also have increased thirst, along with weight loss, restlessness and a rough coat. Both are common in older cats, and both are treatable. See diabetes in cats and hyperthyroidism in cats.
Making water more appealing
Cats prefer fresh, clean water, away from food and litter. Try wide, shallow bowls, a fountain and several locations around the house. Wash bowls daily. Adding water to wet food is a useful way to add moisture. If a sick cat drinks less, call your vet.
When to see a vet
See a vet if your cat is drinking much more than usual for more than a couple of days. Use the US vet directory to find a clinic.
Frequently asked questions
How much water should a cat drink?
Roughly 2 to 4 ounces per 5 pounds of body weight daily, including moisture in food.
Is drinking a lot always a problem?
Dry food, heat and activity can raise intake, but sustained change needs a check.
What disease is most common?
Kidney disease, diabetes and hyperthyroidism are the usual suspects.
Should I restrict water?
No. Always provide plenty of fresh water.
Sources and further reading
Health information changes as research does. These organizations publish guidance worth reading alongside our articles.
- Cat Friendly Homes (AAFP and ISFM)Cat-specific care guidance and a finder for cat-friendly practices.
- Merck Veterinary Manual: cat ownersPlain-language veterinary reference written for owners.
- American Veterinary Medical Association: pet owner resourcesPolicy-level guidance from the national veterinary association.
Tailwisp is independent and written under our editorial policy. Learn who we are, or browse all cat guides.
This article is general educational information, not veterinary advice. Every cat is different. If your cat is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.