Why Is My Cat Always Thirsty?

Cats are known to have a low thirst drive. That’s because they get most of their water from their food and drink fresh water on a limited basis. It’s perfectly normal for a cat to drink as little as 7-9 ounces of water a day. However, if your cat drinks twice this amount and continues to for 2-3 days, that’s a warning sign. Cats shouldn’t always be thirsty, and if they are, it’s for an environmental or health reason.

Your cat might be extra thirsty because it has a medical issue, such as kidney dysfunction, urinary tract infections, liver disease, diabetes mellitus, or hyperthyroidism. Any of these conditions will make your cat thirsty, urinate more often, and even refuse to eat. However, there are also harmless reasons for a cat to drink too much water. The cat may be too hot from a warm day, eating too much dry food, or stressed by its surroundings or another cat.

You shouldn’t worry until the cat is extra thirsty for more than 1-2 days. If your cat is older or has a medical issue already, you should call a vet early. This is also true if the cat shows other negative symptoms alongside it. This may include vomiting, refusal to eat, lethargy, weight loss, fever, diarrhea, and other concerning signs. Drinking a little more than normal is fine, but drinking twice as much or several times an hour is worth being concerned about.

How Much Water Is Too Much for a Cat?

There is no fixed amount of water a cat should drink. The normal amount will vary between each cat based on:

  • Size
  • Breed
  • Weight
  • Diet
  • Age
  • The surrounding climate

On average, it is estimated that a cat should drink between 3.5 to 4.5 ounces for every 5 pounds of weight. If your cat weighs about 10 pounds, it should ideally be drinking 7-9 ounces of water each day. That’s roughly the amount of a small drinking glass.

About 7-9 ounces of water may seem like far too little for a cat. However, domestic cats evolved from desert ancestors and have a limited thirst drive. A feline will get its water from prey or wet cat food. Drinking out of a water dish itself is secondary, and a cat doesn’t need much to get by.

If your cat drinks more than 9 ounces, don’t be alarmed. There are many reasons for a feline to get extra thirsty, and most are satisfied by drinking more. If you offer wet food, for example, the cat will receive moisture from its diet and won’t need to drink as much water. In the summer, your cat may drink more to keep itself hydrated despite the heat.

If the cat consistently drinks more than normal, however, then it’s worth paying attention. The added water itself will not harm the cat. Instead, the sudden thirst is a symptom and indicates an underlying problem. Too much water for a cat is about one-half more or twice its normal amount consistently.

Is My Cat Too Thirsty?

Your cat isn’t going to walk up to you one day and tell you that it’s drinking too much water. Nor will you be able to measure the amount of water left in your cat’s drinking bowl every time it drinks from it. Instead, you will have to be on the lookout. Here are some signs that should immediately tell you that your cat is always thirsty:

  • The cat’s water bowl needs to be filled more often.
  • You catch your feline drinking water from strange places, such as sinks, toilet bowls, puddles, and ponds.
  • Your cat appears to visit its water bowl more often.
  • Your cat sits next to its water bowl and meows, even though it has just quenched its thirst.

These are more obvious and direct indicators that your cat is always thirsty. However, if your cat drinks more because it’s ill, that may not be so easy to figure out.

That’s because, while cats may seem domesticated to us, they are still wild animals. In the wild, any animal that explicitly shows signs of illness or weakness becomes a target for predators. Hence, cats are good at hiding the fact that they are ill, even from their owners. To spot thirst as a result of sickness, check for additional symptoms:

  • Your cat is resting much more than usual and in odd sleeping positions
  • Big changes in a cat’s behavior, such as an active cat becoming lethargic or a calm cat showing signs of aggression
  • Changes in your cat’s appetite, eating more or less than normal  
  • Diarrhea or vomiting from your cat

What Does It Mean When a Cat is Always Thirsty?

If your cat persistently drinks more water than usual, it may be contending with a health issue. In some cases, its body will not process the water it gets, so it drinks more. In others, the cat needs more water to function.

Since cats have a low thirst drive, this can’t be ignored. Once it’s gotten this far, more water won’t fix whatever has caused the feline to go against its own biological urges. In the medical world, increased thirst levels are known as polydipsia. The most common causes of polydipsia in cats are:

Kidney/Renal Dysfunction

This is an illness that affects older cats. It tends to get progressively worse over time. A cat’s kidneys are responsible for maintaining a healthy balance of fluids in the body and excreting liquid waste.

According to the Journal of the American Veterinary Medical Association, polydipsia, or overconsumption of water, was found to be an important factor in diagnosing cats with chronic kidney disease (CKD)

Although renal dysfunctions and diseases are not reversible, appropriate support and treatment for your cat are necessary. Kidney dysfunction can’t be diagnosed or treated at home. You should take your cat to the veterinarian for a full evaluation. The expert can then recommend treatments that can help increase your cat’s quality of life.

Urinary Tract Infection (UTI)

Just like renal dysfunctions, UTI is a catch-all term for many different kinds of afflictions. Older cats often get urinary tract diseases that can affect the urethra or the bladder. Such issues are so common among felines that these medical conditions have their own name: ‘Feline Lower Urinary Tract Disease’ (FLUTD).

In cats, urinary tract diseases are caused by several different factors. They range from simple issues, like a bladder stone, or serious ones, like a bacterial infection. According to The Journal of Nutrition, a cat’s diet or the specific nutrients it consumes may trigger some or all of these developments.

To cap things off, your feline may naturally be more susceptible to a urinary tract disease. This is true if it’s:

  • An older or middle-aged cat
  • Neutered
  • Overweight 
  • Inactive and has little-to-no exercise
  • Eating a purely dry diet

A urinary tract infection can lead to excessive discomfort or pain, especially while urinating. Other signs that your cat has a urinary tract infection include:

  • Urinating more often  
  • Blood found in cat’s urine
  • Urinating outside the litter box in unusual places
  • Over-grooming (and subsequent hair loss around the infected area)
  • Inability to pass urine for an unusually long period of time
  • Drinking too much water

If you detect any of these signs in your cat’s behavior, make sure to take it to the vet. Only a veterinarian can confirm whether or not your cat has a urinary tract disease. If it does, an expert will be able to recommend a treatment for it.

how much water is too much for a cat?

Liver Disease

If your cat has excessive thirst long-term, it may have liver disease. Cats, and especially senior cats, are at an increased risk of liver disease. That’s because they lack certain metabolic pathways in the liver that would help them get rid of various toxins.  Possible signs of liver disease in your cat are:

  • Loss of appetite
  • Drinking too much or too little water
  • Extreme lethargy – even more than usual for a cat
  • Sudden weight loss
  • Fever
  • Vomiting
  • Jaundice (yellowing of the gums, eyes, and skin)

There are many underlying signs of liver disease, and often, they are vague indicators of your cat’s ill health. If you detect any of these changes in your cat’s physical state or behavior, contact a medical professional. Only a vet will be able to confirm whether or not your cat is suffering from liver disease.

To diagnose the condition, your vet may recommend a liver biopsy. While it sounds invasive, it’s an effective way of confirming liver disease and identifying what leads to it. A liver biopsy will help your vet find the right treatment.

If your cat is dehydrated due to its underlying liver condition, supportive treatments can be helpful to bring back your cat’s strength. Remaining dehydrated while suffering from a liver condition can prove fatal. After all, your cat’s metabolism will slow down too much to deal with the problem.

To support your dehydrated cat through its recovery, your veterinarian may recommend using intravenous fluids. This will be matched with nutritional support, like adding vitamin K to your cat’s diet.

Diabetes Mellitus

Diabetes mellitus, also known as ‘sugar diabetes,’ is a common illness. It’s caused by either a relatively low amount of insulin. Insulin is vital to controlling the body’s level of glucose (sugar) and maintaining normal levels.

Diabetes mellitus is prevalent in older felines. The good news is, it can easily be diagnosed and managed, although management is different for each cat. The disease appears more often in male cats than female ones and also in neutered cats. Diabetes is more likely to occur if your feline is overweight.

According to the Journal of Veterinary Internal Medicine, drinking too much water is common in felines with diabetes mellitus. This is also paired with symptoms like:

  • Increased urination
  • Increased appetite
  • Dramatic weight loss
  • Unkempt or poor condition of the fur
  • Weakness in the legs
  • Lethargy
  • Signs of bladder and urinary tract infections

If you detect any of these behavioral or physical changes in your cat, take it to the vet. Diabetes is usually diagnosed via a urine and blood sample. It’s not too difficult or costly to treat.

Hyperthyroidism (Overactive Thyroid Gland)

Hyperthyroidism can affect cats of any age, but it predominantly appears in older cats. It is caused by the overproduction of thyroid hormones from the thyroid gland. These glands are found in the neck.

A major function of thyroid hormones is to regulate the cat’s metabolic processes. Hence, the over-production of thyroid hormones may cause your cat to burn up energy far too rapidly. As such, it will suffer from weight loss and increased appetite.

Your cat may also become overly thirsty and need more water to function like it used to. Even if your cat drinks enough, however, that doesn’t mean it won’t get ill. This condition can wear down and burn out a cat if left unattended.  The classic signs of an overactive thyroid gland in your cat are:

  • Dramatic weight loss
  • Increased appetite
  • Increased thirst
  • Restlessness or increased activity
  • Poor and unkempt fur coat
  • Increased heart rate
  • Diarrhea and vomiting
  • Noticeable heat intolerance
  • Severe weakness and/or lethargy

If left untreated, hyperthyroidism can have profoundly negative consequences on your cat’s health. For example, it could lead to hypertension and an increased risk of heart failure. Hypertension can also damage other vital organs and body parts such as the:

  • Muscles
  • Eyes
  • Brain

Hyperthyroidism can be easily diagnosed and treated through drug therapy. In cats whose hyperthyroidism has gone untreated for far too long, your veterinarian may recommend surgical treatment. This involves the surgical removal of the affected tissues and usually results in curing the cat’s overactive thyroid gland.

Why Is My Cat Suddenly Drinking A Lot Of Water?

Of course, it’s not all doom and gloom. Even with the possible medical concerns, you don’t need to rush your cat to the vet just because it’s drinking a lot of water suddenly. It may have a normal, non-medical reason for it.

A cat’s need for water can change over time throughout its life, based on various environmental and physical factors. Even that particular day could’ve made your feline thirsty, and it’ll be back to normal tomorrow. Before you call a vet, evaluate if any of these factors could be making your cat extra drink extra water:


During the hottest months of the year, your cat may be losing far more water from its body than it is consuming. This means it will feel thirsty more often and drain its water bowl at a more rapid pace. The normal 7-9 ounces for a cat may become 10-14, or even more. During summer, your cat may also start drinking from unusual places, like the:

This behavior is completely normal. Unless you suspect that your cat is drinking too much due to an underlying medical condition, let it continue. Without additional symptoms, and with a good reason like too much heat, your cat knows its own water consumption needs better than anyone.

With that said, excessive heat will turn out bad for your cat, no different than organ or gland failure. During the summer months, make sure your cat has constant access to shade and clean water. If it’s drinking twice as much each day, then help your feline cool down. This may include turning on fans or an AC unit or keeping the cat indoors until the temperatures even out.

Eating Dry Food

In the wild, cats usually fulfill their water consumption needs through the food they eat. For both ancient cats and modern predators, the carcass of a prey animal contains more than enough water to keep them hydrated for some time. Although, during the drier months of the year, even wild cats try to find watering holes for fresh water sources.

Domesticated cats, however, are usually not given (or able to find) fresh carcasses regularly. The dry kibble that’s usually fed to cats has nutritional value, but it does not contain much water. If your cat’s meals are generally dry, it might result in dehydration. This will cause your feline always to be thirsty.

If you suspect that your cat is drinking too much water for this reason, change up its diet. Try adding some wet food into the daily meals. The cat should enjoy the flavor and the boost to its kidneys.  


If your cat is stressed, it may start drinking more water than usual. That’s because, when it’s scared, uncertain about its surroundings, or feeling aggressive, its body is on high alert. This burns energy and wears out its stored-up resources. To replenish these, your cat may become voraciously hungry or extremely thirsty.

A cat might be stressed about staying indoors for too long. It may also find itself stressed out during the mating season, especially if it can sniff out potential mates in the area. If your cat is involved in an ongoing territorial battle with another cat, this can also cause a lot of stress.

In the short term, drinking more water is a fine response. It won’t harm your cat, and the feline will keep up its own hydration levels. However, like with other medical issues, drinking water isn’t a problem; it’s a symptom. Constant exposure to stress can wear down the body, eventually leading to sickness in your cat.

That makes it important to uncover what’s bothering your pet and limiting or removing that factor. In the meantime, let your cat have full access to as much water as it needs. It’s better for it to drink too much while you’re solving the problem rather than getting dehydrated and then sick in the meantime.

is it bad if my cat drinks a lot of water?

Why Is My Old Cat Drinking A Lot Of Water?

It’s natural for older cats to drink slightly more than before. This shouldn’t double or quadruple, but half-again as much water is fine. This is because:

  • The cat’s body is aging, so it’ll store less water and need more for its joints, organs, and muscles.
  • Older cats tend to eat slightly less, so they will need more water to compensate for what they’re missing in their diet.
  • The elderly cat may have a health condition or disease that makes it thirsty or requires it to drink more water than normal.

These are all legitimate reasons for your aging cat to drink more water. You should only be concerned if the feline has a remarkable uptick out of nowhere. As with all cats, drinking too much for 2-3 days or showing unquenchable thirst should warrant a call to your vet.

Most of the conditions and illnesses that are associated with over consumption of water are more likely to afflict an older cat. This includes:

  • Urinary tract infections
  • Renal dysfunctions
  • Liver problems
  • Diabetes mellitus

While all cats should see a vet if they manifest symptoms, time is of the essence with older cats. They will have more delicate immune systems and have more difficulty recovering from illness. If you find your elderly cat draining its water bowl more than once, or drinking out of unusual places, push up your vet appointment.

Cat Drinking a Lot of Water and Eating Less

Drinking more or less water is nothing to worry about at first. However, if the cat also begins eating less than normal, you should pay attention. When paired together, this is an obvious symptom of:

  • Stress
  • Overheating
  • Disease
  • General illness

A feline can compensate for a lack of water with wet food. The same cannot be said in reverse. A cat that eats little for no reason is likely unable to eat or feeling unwell. It’s unable to eat, unwilling to eat, or cannot properly digest the food. Whatever causes your feline to drink an excessive amount of water to avoid dehydration or to sate a need that cannot be fulfilled.

During the summer, this could mean your feline has heatstroke or sun sickness. In this case, try to cool down your home and offer shady places where your feline can enjoy a reprieve. If the cat is stressed, then remove whatever is scaring it and provide it with a safe hiding spot immediately.

If there’s no obvious cause, then contact your vet. The feline is likely dealing with a medical issue, especially if it’s:

  • Older
  • Neutered
  • Overweight

It may be contending with kidney disease, hyperthyroidism, or other issues. A vet will be able to uncover the cause and provide treatment, so your cat begins eating normally again.

Cat Constantly Drinking Water And Urinating A Lot

If your cat is urinating frequently, then it could have 3 possible explanations. The cat may be:

  • Drinking more for natural, safe reasons and need to pass this extra water like normal
  • Struggling with a medical issue that’s causing it to drink too much and peeing too much is a byproduct
  • Suffering from an illness that’s inflaming its urinary tract or kidneys, directly causing it to pee a lot

Before you can tell which one applies to your cat, ask yourself this question: Is your cat peeing often or peeing in large amounts?

Frequent urination, to the point of being disruptive to life, is called pollakiuria. Meanwhile, increased urine volume is known as polyuria. If your cat is peeing more often, this could be a sign of kidney or bladder problems. It’s also a common indicator of diabetes.

If your cat is peeing in larger amounts, however, this could be a sign of increased blood glucose levels. It may even signal that your cat has an overabundant blood salt content. Furthermore, kidney disease could play a role in this kind of behavior, but these kidney problems are usually distinct from those that cause increased urination frequency.

No matter the case, both can be treated with the help of a vet. If your cat is always thirsty, be sure to watch out for additional symptoms and see if it persists over multiple days. If it’s not the heat, stress, or another simple explanation, a vet should always be your next choice.

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Richard Parker

I'm Richard, the lead writer for Senior Cat Wellness. I'm experienced in all cat health-related matters, behavioral issues, grooming techniques, and general pet care. I'm a proud owner of 5 adult cats (all adopted strays), including a senior cat who is now 20.

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