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Why is My Cat Drinking a Lot of Water?

Cat drinking water from outdoor bowl
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Cats are not big water drinkers—they need half as much water as dogs per pound of body weight. So when you notice your cat drinking a lot of water, or maybe even downing it and begging for more, it may be a red flag.

How much water is too much? What causes your cat to drink so much water? And, more importantly, what should you do about it? Read on for answers.

How Much Water Should a Cat Drink?

Two cats with heads tilted looking to owner for answer

Cats typically drink 18 to 27 mL of water per pound of body weight per day. An average 10-pound cat drinks approximately 180 to 270 mL of water per day, which is equivalent to around ¾ to 1 cup of water each day. 

Each individual cat will vary in how much water they need to drink, and what is normal for your cat may fall a little outside this range. 

Factors that could alter how much water is required include

Diet. Canned cat food has water content already, so your cat will drink a little less if they eat a wet food. Also, diets high in sodium require more water.

Environment. Warmer months or higher humidity require more water to stay hydrated, especially if your cat is active.

Age. Very young cats drink more than adults. Young kittens under 8 weeks of age require as much as 80 mL of water per pound of body weight! 

Health. If your cat has a medical condition, she may need to drink more water to stay hydrated.

Medications. Certain medications increase thirst and/or urine output in cats.

If you are reading this article because you are concerned with how much your cat is drinking, try measuring out the amount of water you put in the bowl each morning. The next morning, measure how much is left (wait until 24 hours have passed). Be sure to never limit the amount of water your cat wishes to drink! She must always have access to as much water as she wants.

Cats Drinking Water: How Much is Too Much? 

Cat drinking water from a faucet

Polydipsia is the condition of a cat drinking too much water. It is usually caused by polyuria, meaning your cat’s body is producing more urine and needs more water to do so. Shorthand for these two cat health conditions is PU/PD.

Cats vary in how much water they drink day to day. If your kitty is particularly thirsty one day (maybe due to running around on a hot summer day), the next day her drinking would be less. This would be normal variation and no reason to worry. 

But if your cat is consistently (each day) drinking more than 45 mL per pound of body weight per day, she likely has polydipsia. A 10-pound cat would need to drink more than 450 mL of water per day to have polydipsia, or about 2 cups.

You may not notice a subtle increase in your cat’s water drinking, but look for signs like:

An empty water bowl more frequently

  • Waiting by the water bowl for more, meowing until it’s refilled
  • Drinking an entire water bowl or most of one in one sitting
  • Larger volume of urine in the cat litter box (bigger clumps and/or higher number of them)
  • Urine outside of the cat litter box

Why Is My Cat Drinking a Lot of Water? Common Causes

Cat looking out the window at owner

There are many health reasons cats will drink too much water and be diagnosed with polydipsia. The three most common causes include:

Chronic Kidney Disease

Around 1-3% of all cats have chronic kidney disease. Over time kidneys become more and more damaged. Kidneys are partly responsible for maintaining your cat’s balance of water, and when kidneys are damaged, they cannot hold onto water like they should. All the water goes into the urine instead. This makes your cat increasingly thirsty.

Hyperthyroidism

Up to 11% of older cats are diagnosed with hyperthyroidism. The thyroid gland produces thyroid hormone, which is responsible for growth, metabolism, and impacts the brain. When the gland produces too much hormone, metabolism becomes really high and the effect on the brain can cause changes in behavior. When metabolism increases, so does thirst. Also, thyroid hormone blocks antidiuretic hormone (ADH) from interacting with the kidneys. This hormone allows the kidneys to keep water in the body and not put water into the urine. If ADH cannot interact with the kidneys, a lot of urine and thirst occur.

Diabetes Mellitus 

Around 0.5% of all cats have diabetes mellitus. Diabetes mellitus occurs when your cat does not have enough insulin. Insulin allows blood sugar (glucose) to enter the liver, muscle, and fat and provide energy. If there is not enough insulin, glucose gets increasingly high with nowhere to go. The kidneys push glucose into the urine, and through osmosis, water follows glucose to dilute the urine. Since your cat produces too much urine to rid the body of glucose, she becomes very thirsty.

Cat drinks water from the tap

Other less common causes of polydipsia in cats include:

Liver disease. Liver disease in cats can occur for a huge number of reasons, including viral, bacterial, fungal, parasitic, inflammatory, or cancerous reasons. When liver disease is severe, multiple components the liver normally makes cannot be made and this affects water intake. For example, the liver stops making urea which normally allows the kidneys to retain water.

Medications. Many medications affect thirst and urination. Common medications include steroids (such as prednisolone), phenobarbital (used for seizures), or diuretics (used to decrease body water for conditions like congestive heart failure).

Hypercalcemia. Many conditions can cause too high of calcium in a cat’s body such as chronic kidney disease, vitamin D toxicity, and cancer. When calcium is very high, it prevents ADH from interacting with the kidneys. This prevents the kidneys from keeping water in the body, so a lot of urine and thirst occurs.

Cancer. The reason cancer affects thirst depends on where the cancer is, such as liver cancer for reasons above, bladder cancer for increasing urine or if cancer causes hypercalcemia. 

Pyometra. Pyometra is an infection of the uterus. If your cat has not been spayed, she may develop this common condition (which does not always result in polydipsia). Pus fills the uterus and often leaks outside of the body through the vulva. The reason pyometra causes polydipsia (due to polyuria) is uncertain.

What to Do When Your Cat Is Drinking Too Much Water

Woman taking notes in a notebook

If you suspect your cat is drinking too much water, measure it out as described earlier in this article and keep a log of how much water your cat is drinking. 

On your log record any changes in your cat’s behavior or health. Ask yourself questions like:

  • Has her activity decreased?
  • Has her appetite changed?
  • Has her weight changed?
  • What color is her urine?
  • How many clumps of urine are there and approximately what size? Is this more or less than in the past?
  •  Is there any urine in the house outside of the litter box?
  • Has your cat’s diet changed lately?
  • Has your cat started any new medications?
  • Has your cat eaten or gotten into anything she wasn’t supposed to?
  • Has there been any vomiting or diarrhea?
  • Are there any new behaviors you haven’t seen before?

If your cat is consistently drinking more than 45 mL of water per pound of body weight each day, or if you notice any other signs such as decreased activity, increased appetite, and decreased weight you should bring your cat to the veterinarian as soon as possible.

What to Expect at the Vet

Cat at the vet having an exam

Your veterinarian will examine your cat and ask many questions. If you have answered the questions above and recorded how much water your cat is drinking, you will be prepared to answer the veterinarian. 

Without running tests, your veterinarian is unlikely to be able to diagnose the exact cause of your cat’s excessive drinking. Bloodwork is a standard first step along with testing the urine, including a culture to look for infection. Oftentimes your veterinarian will recommend thyroid testing on the bloodwork as well.

These initial tests will almost always diagnose the issue, since that is how the most common causes are diagnosed. If the tests do not reveal an answer, next steps may include X-rays to look for pyometra (if your cat is a female and has not been spayed) or cancer. Many other specific blood tests may be performed such as bile acids to assess liver function, fructosamine levels to evaluate for diabetes, leptospirosis testing, and various other hormone tests to help get to a conclusion.

Kidney Support Products for Cats

Now that you know some of the medical and behavioral reasons for increased water consumption in cats, what next? After talking to your veterinarian and having your cat examined, ask about kidney issues.

Here are some of our favorite non-prescription kidney support supplements for cats:

All featured products were chosen at the discretion of the Great Pet Care editorial team and not directly recommended or endorsed by the author of this article. Great Pet Care may make a small affiliate commission if you click through and make a purchase.

Great Pet Great Kidneys Soft Chews For Cats

Great Pet Great Kidneys

Although there is no cure for kidney disease in cats, there are things that can be done to slow it down and stop it in its tracks. When kidneys lose their function, your cat can become very sick. Fortunately, there are supplements available to help. Great Pet’s Great Kidneys Soft Chews For Cats boost their immune system to fight infection while promoting healthy kidney function. Because the product is dispensed in a tasty chewable format, cats enjoy a delicious treat while its contents support their kidneys.

Highlights

  • Proudly made in the USA
  • Appetizing chicken flavor appeals to cats’ taste buds
  • Made with Astralagus herb and Rehmannia herb for peace of mind
  • It may help prevent urinary tract infections
  • Boosts a cat’s immune system
  • One chew a day for smaller sized cats, more for larger cats
  • Generous 60-count container

Things to Consider

  • The container must be stored in a cool, dry place
  • Made for cats one year of age and older

Hill’s Prescription Diet k/d Kidney Care Wet Cat Food

Hills Kidney Care Wet Cat Food

A team of veterinarians and nutritionists at Hill’s developed a diet to support your cat’s kidney function and help her sustain muscle mass. As cats age, kidney issues may occur. Fortunately, under your veterinarian’s care, cats can thrive for many years with proper diet and nutrition as part of the overall plan. Because Hill’s performs five million quality and safety checks per year to ensure high quality, you can feel good feeding your cat with kidney disease this food.

Highlights

  • Available in several wet form flavors to entice picky cats.
  • Reduced phosphorus and sodium help protect vital kidney function
  • Contains more amino acids than daily requirements to support the cat’s natural ability to build lean muscle
  • Veterinarian-recommended therapeutic pet food
  • Contains therapeutic levels of L-carnitine and omega-3 fatty acids

Things to Consider

  • Product must be sold under the supervision of a veterinarian. This information must be provided at checkout.
  • Adjust feeding amounts as necessary to maintain your cat’s optimal weight according to your veterinarian.

Pet Wellbeing Kidney Support Gold for Cats

Pet Wellbeing Kidney Support Gold for Cats

A few drops of Kidney Support Gold can help support your cat’s immune system functionality against kidney issues. It also helps to moderate normal hydration, urination, and thirst in a powerful herbal formula. Medicine for cats can be hard on their delicate systems, but Kidney Support Gold is designed as a gentle, all-natural formula.

Highlights

  • Supports the nephrons (part of the kidney that filter blood)
  • Helps support normal fluid and electrolyte balance
  • Helps maintain normal levels of blood urea and creatinine, which are excreted by the kidneys
  • Developed by on-staff holistic veterinarians
  • Easy to administer dropper included

Things to Consider

  • Must be given twice daily (one drop per every two pounds of body weight)
  • Safe use in pregnant cats or cats intended for breeding has not been proven
  • Examination by a veterinarian is recommended prior to administering this product

Vet Classics Cranberry Comfort Urinary Tract Pet Supplement

Vet Classics Cranberry Comfort Supplement

For cats who need additional support with their urinary tract, Vet Classics Cranberry supplement may help. A healthy urinary tract is important for cats with kidney issues. It is veterinarian formulated and recommended and made in the USA. The key ingredients work together to help keep your cat’s bladder lining healthy and to support and maintain her urinary tract.

Highlights

  • Contains wholesome ingredients including cranberry, Echinacea, Marshmallow root, Oregon grape root, and vitamin C.
  • Handy 65- or 120-count chews per container
  • Made in an FDA audited, cGMP compliant facility
  • The product maintains the quality seal from the National Animal Supplement Council (NASC)
  • Also available in a powder form

Things to Consider

  • Give twice daily for one to three weeks, then no more than twice weekly or per your veterinarian’s instructions
  • Number of chews depends on the weight of your cat
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