cat drinking a lot of water and meowing
Cat Food and Hydration

Why is My Cat Always Thirsty?

It’s normal for a cat’s water consumption to increase during warmer weather. But sometimes excessive drinking in cats, especially when accompanied by other symptoms, is a cause for concern.

If your cat is drinking a lot of water, it may have polydipsia (excessive thirst). A cat with polydipsia may drink 60 ml per kg of body weight per day. Causes range from behavioral to pathological, such as diabetes, hyperthyroidism, fever, and urinary tract disease.

Cats are exceptional at concealing signs of illness and disease. It may only be noticed due to subtle behavioral changes, such as increased thirst. Monitoring your cat’s drinking patterns can help you tell if your cat’s desire to drink constantly is due to hot weather or a health condition.

How Much Water Should My Cat Drink Per Day?

Cats should drink 60 ml per kg of their body weight each day.

For example, a 4 kg (8.8lb) cat should be drinking 240 ml or one cup of water daily to ensure that it’s body functions optimally.

When deciding the amount of water your cat should drink every day, it’s also vital that you consider your cat’s diet.

Dry food is 10% water, whereas wet food can be 80% water. A 4 kg cat on a wet food diet may only need to drink 30 ml of water every day, whereas a 4kg cat on a dry food diet may need over 200ml of water per day.

Perhaps your cat’s increased thirst has other symptoms, such as increased or decreased urination, appetite changes, lethargy, vomiting, increased sleep, or diarrhea. If so, take your pet to the vet with a urine sample.

old cat drinking a lot of water

Causes of Sudden Increased Thirst in Cats

Cats are believed to be evolutionarily predisposed to consume the majority of their liquids from solids. Cats feed frequently in the wild, hunting small animals throughout the day.

If your cat’s drinking habits have changed suddenly, then you need to find out why. There are 3 different causes of excessive thirst in cats:

CompensatoryYour cat’s diet is primarily composed of dry or high-sodium foods, which makes it thirstier.
EnvironmentalIncreased heat causes your cat to pant more to cool itself, allowing it to lose more water.
PathologicalSickness can also increase your cat’s water requirements. Examples include vomiting, diarrhea, diabetes, kidney disease, and hyperthyroidism.


Cats can experience numerous types of infections that cause fever, but it can be difficult to spot whether your cat is feeling unwell. Sometimes fever can cause your cat to drink more water than usual.

According to the Journal of Feline Medicine and Surgery, the most common cause of fever, or pyrexia in cats was infectious peritonitis, followed by inflammatory conditions. The only way to tell if your cat has a fever is to take its temperature using a thermometer.

Temperatures ranging from 100.4 to 102.5 degrees Fahrenheit are considered normal for cats. Anything above 102.5 degrees Fahrenheit indicates that your cat has a fever, and a temperature higher than 106 degrees Fahrenheit can be harmful to its organs.

Fever in cats usually occurs when the immune system has been triggered by conditions, such as:

  • A bacterial, viral or fungal infection
  • Injury from trauma
  • A tumor
  • Certain medications
  • Diseases such as lupus

Fever may be accompanied by these other signs, which include:

  • Loss of appetite
  • Grumpiness
  • Depression
  • Lethargy or lack of activity
  • Increased or decreased drinking
  • Decreased grooming
  • Rapid breathing or shivering

Your cat may also show other signs of sickness, such as vomiting, sneezing, and diarrhea.

Kidney Failure

According to Veterinary Pathology, kidney disease is the most common metabolic disease in domestic cats. Left untreated, this condition can have severe health and lifestyle implications.

Cats are obligate carnivores and protein is a vital part of their diet. The kidneys have to work harder, so cats that are over 7 years of age may start to develop kidney disease. The incidence of kidney problems rises with age.

cat drinking a lot of water and throwing up

In the case of chronic kidney disease, there is no cure. However, early diagnosis and proper home care can increase the length of your cat’s life.

Some kittens can also be born with kidney disease. Toxins, trauma, and infection are other causes.

There are two types of kidney failure in cats:

Acute Renal failThis develops suddenly and is often reversible if diagnosed early. It can happen due to poisons such as toxic plants (e.g. lilies), antifreeze, cleaning products, human medications, trauma to the pelvis or bladder, shock, dehydration, kidney infection, heart failure, and urethral blockages.
Chronic Renal Failure This occurs mostly in middle-aged and older cats. It can take months or years to develop. Chronic kidney failure is harder to treat, and its cause isn’t understood. Some vets believe it may be due to kidney blockages and infections, high blood pressure, thyroid issues, advanced dental disease, or cancer.

Cats with kidney failure may drink a lot of water because they are trying to replace the water lost due to frequent urination.

Kidney failure can cause your cat to urinate more because it isn’t able to hold water any longer. Frequent urination outside the litter box is another sign. Also, your cat may be drinking a lot of water and losing weight. Other signs to look out for include:

  • Decreased appetite and weight loss
  • Bad breath (ammonia-like smell)
  • Vomiting
  • Diarrhea
  • Bloody, cloudy urine
  • Brownish tongue
  • Dry coat
  • Mouth ulcers on the tongue and gums
  • Constipation
  • Weakness
  • Apathy

Diabetes Mellitus

This is the body’s inability to respond to or produce enough insulin. This is a hormone required by your cat’s body to balance blood sugar levels.

If left untreated, diabetes can lead to weight loss, dehydration, loss of appetite, stress and anxiety, severe depression, motor function problems, coma, and even death.

Type 1 DiabetesA decrease in insulin production in the body causes glucose concentrations to exceed normal levels.
Type 2 DiabetesThe cells in the body are unable to respond properly to insulin, causing glucose levels to increase.

Increased thirst (polydipsia) and urination are the main symptoms of diabetes. Diabetes is far more common in overweight cats.

Diagnosis of feline diabetes involves conducting blood and urine tests to check glucose concentrations.


Hyperthyroidism is a common glandular disorder in cats often caused by an overactive thyroid gland.

An overactive thyroid gland produces large amounts of thyroxin hormone, leading to a faster metabolism, high heart rate, and high blood pressure.

Hypothyroidism can occur in all breeds and both genders of cats, but it’s most common in older cats, with an average age of 12-13 years.

cat drinking a lot of water and losing weight

Clinical signs of hyperthyroidism are increased appetite (67-81% of cases) and weight loss (95-98% of cases).

Other signs include excessive thirst, hyperactivity, increased urination, panting, diarrhea, a messy appearance, and increased shedding. Your cat may also be drinking more water and throwing up.

Urinary Problems

If your cat has been drinking a lot of water but not peeing, it could be due to a urinary problem. Cats strain more and have difficulty urinating. If you notice no urine coming out, your cat may have a blocked bladder.

Not all reasons for urinary problems are medical, though. Stress and anxiety caused by changes in the environment, new additions in the house, changing the litter tray or cat bed location, and loud noises are causes.

A dominant cat in your cat’s territory or dietary change are other causes. Environmental stress can contribute to Feline Idiopathic Cystitis (FIC).

Another cause could be solid crystals forming in your cat’s urine, which can result in urethral plugs or bladder stones.

Signs of urinary problems are your cat constantly trying to urinate and straining while peeing. You may also notice that your cat’s urine trickles instead of coming out smoothly. In severe cases, you may notice fatigue, vomiting, your cat crying out in pain, and blood in the urine.

A cat that is always thirsty when it’s not hot is likely to have a medical condition (diabetes, fever, hyperthyroidism, kidney failure, or a urinary problem. Tests will need to be run by a vet to find out why your cat is drinking more than normal. Early diagnosis and treatment are crucial.