Why Is My Cat Drinking More Water? Common Causes, When to Worry and When to See Your Vet
- 10 minutes ago
- 13 min read
As cat owners, we quickly become familiar with their little routines. We know where they like to sleep, how loudly they purr when they're happy and exactly when they'll appear in the kitchen asking for breakfast.
Because cats are such creatures of habit, even small changes in their daily behaviour can tell us something important.
One change that should never be ignored is drinking more water than usual.
Perhaps you've noticed you're refilling the water bowl more often, your cat has suddenly become fascinated by the kitchen tap or they're making more frequent trips to the bowl throughout the day. Sometimes there's a simple explanation, but increased thirst can also be one of the earliest signs of an underlying health condition.
At Roundwood Vets, we often hear owners say, "Apart from drinking more, they seem absolutely fine." That's something we take seriously because cats are remarkably good at hiding illness. By the time they show obvious signs that they're unwell, they've often been quietly compensating for quite some time.
The good news is that many of the conditions that cause increased thirst can be managed successfully, especially when they're diagnosed early. Recognising the signs and seeking advice promptly gives us the best opportunity to identify any problems and put a plan in place to help your cat stay happy and healthy.
In this guide, we'll explain why cats drink more water, what might be causing it, when it's time to arrange a veterinary appointment and how recognising subtle changes early can make a real difference.
Contents
How Much Water Should a Cat Normally Drink?
One of the first questions owners ask is:
"How much water should my cat actually be drinking?"
The answer isn't always straightforward.
A healthy cat typically drinks around 40 to 60ml of water per kilogram of body weight each day, although this can vary depending on several factors, including their diet, activity levels, age and the temperature of their environment.
For example, a healthy 4kg cat may drink somewhere between 160 and 240ml of water over 24 hours, but this is only a guide. We don't expect owners to measure every drop their cat drinks, and in most cases it isn't necessary.
Instead, it's much more helpful to understand what's normal for your own cat.
Some cats seem to visit their water bowl only occasionally, while others prefer frequent small drinks throughout the day. Both can be perfectly normal.
Diet Makes a Big Difference
One of the biggest influences on how much a cat drinks is what they eat.
Cats fed predominantly wet food often appear to drink very little because canned food contains around 70–80% water. Much of their daily hydration comes directly from their meals.
Cats eating mainly dry food naturally need to drink more because dry biscuits contain very little moisture.
This means that two perfectly healthy cats living in the same household may have completely different drinking habits simply because they're eating different diets.
Rather than comparing your cat with another cat, it's much more useful to notice changes in their own normal routine.
How Can I Tell If My Cat Is Drinking Too Much?
Most owners don't measure exactly how much their cat drinks each day, and that's absolutely fine.
Instead, you may notice small changes that gradually catch your attention.
Perhaps you're refilling the water bowl much more often than usual, or your cat has suddenly started asking for the tap to be turned on. Maybe they've begun drinking from unusual places such as the bath, the shower tray or even a plant pot outside.
Other signs include:
Visiting the water bowl much more frequently.
Drinking for longer than they used to.
Emptying the bowl overnight.
Seeming thirsty immediately after eating.
Waking during the night to drink.
Increased thirst is often accompanied by increased urination, something vets refer to as polyuria and polydipsia.
You may also notice:
Larger clumps in the litter tray.
A litter tray that fills up more quickly.
Asking to go outside more often.
Urinating in unusual places around the home.
Wet bedding in older cats who previously had excellent toilet habits.
These changes don't necessarily mean something is seriously wrong, but they are your cat's way of telling us that something has changed.
Why Do Older Cats Often Drink More?
One of the most common questions we hear is:
"Isn't it just old age?"
It's certainly true that increased thirst is more common in older cats, but getting older isn't actually the cause.
Instead, senior cats are more likely to develop health conditions that affect how their bodies regulate water.
These include:
Chronic Kidney Disease (CKD)
Hyperthyroidism
Diabetes Mellitus
High blood pressure
These conditions often develop slowly over many months, which means the earliest signs can be very subtle.
You may not notice dramatic changes in your cat's behaviour. They may still greet you at the door, enjoy their meals and curl up beside you on the sofa.
The only difference may be that they're spending a little longer at the water bowl.
This is one of the reasons we recommend regular senior health checks. Routine examinations, together with blood and urine tests where appropriate, can often identify problems long before they become advanced.
Early diagnosis frequently means more treatment options, better long-term management and, most importantly, a better quality of life.
Common Causes of Increased Thirst in Cats
There isn't one single explanation for increased drinking.
Sometimes the cause is relatively minor, while in other cases it may indicate an illness that requires treatment.
The important thing to remember is that increased thirst is a symptom, not a diagnosis. Our job is to discover what's causing it so we can provide the most appropriate care.
Let's look at the most common reasons.
Chronic Kidney Disease (CKD)
One of the most common causes of increased thirst in older cats is Chronic Kidney Disease, often shortened to CKD.
The kidneys perform many essential jobs every minute of every day. They filter waste products from the bloodstream, regulate water balance, maintain healthy levels of important minerals and help control blood pressure.
Healthy kidneys are remarkably efficient at conserving water by producing concentrated urine.
As kidney disease develops, this ability gradually declines.
Instead of producing concentrated urine, affected cats lose more water through their kidneys. To replace that lost fluid, they naturally begin drinking more.
Often, owners notice this long before their cat appears obviously unwell.
Other Signs of Kidney Disease
As the condition progresses, you may also notice:
Weight loss.
A reduced appetite.
Vomiting.
Sleeping more than usual.
A dull or unkempt coat.
Bad breath.
Muscle loss, particularly along the spine.
Some cats remain bright and affectionate despite these changes, which is why routine health checks and paying attention to subtle signs at home are so valuable.
Why Early Investigation Matters
Hearing that increased thirst can sometimes be linked to kidney disease may sound worrying, but it's important to remember that early diagnosis gives us the best opportunity to help.
Although Chronic Kidney Disease cannot usually be cured, many cats continue to enjoy a happy and comfortable quality of life for months or even years with the right combination of diet, medication, regular monitoring and supportive care.
Cats are incredibly resilient, and many adapt remarkably well when treatment begins before they become seriously unwell.
Sometimes, noticing something as simple as an empty water bowl more often than usual is the first step towards helping your cat feel their best for many years to come.
Diabetes Mellitus
Diabetes mellitus is another common cause of increased thirst in cats, particularly in middle-aged and older cats.
Diabetes develops when the body can no longer regulate blood sugar properly. This may be because there isn't enough insulin being produced, or because the body's cells no longer respond to insulin as they should.
As blood glucose levels rise, excess sugar spills into the urine. Water follows the sugar, causing your cat to produce larger amounts of urine. To replace the fluid they're losing, they naturally become much thirstier.
For many owners, drinking more water is one of the first signs they notice.
Other Signs of Diabetes
As well as increased thirst, you may notice your cat:
Urinating more frequently.
Losing weight despite eating well.
Having an increased appetite.
Becoming quieter or sleeping more.
Developing weakness in their back legs, making them appear to walk with their hocks closer to the ground.
These signs can develop gradually, so it's easy to put them down to ageing. Fortunately, diabetes is a condition we can often manage very successfully.
Treatment usually involves insulin injections, dietary management and regular monitoring. Some cats even go into diabetic remission, meaning they no longer need insulin, particularly if treatment begins early.
The sooner diabetes is diagnosed, the better the chances of achieving good long-term control.
Hyperthyroidism
Hyperthyroidism is one of the most common hormonal conditions affecting older cats.
The thyroid glands, located in the neck, produce hormones that control your cat's metabolism. When these glands become overactive, the whole body effectively speeds up.
Although cats with hyperthyroidism often seem bright and active, they're actually working much harder than normal.
One of the common signs is drinking more water.
Other Signs of Hyperthyroidism
You may also notice:
Weight loss despite a good appetite.
Increased hunger.
Restlessness or being more vocal.
Vomiting.
Diarrhoea.
A scruffy or greasy coat.
An increased heart rate.
Many owners are surprised that their cat seems happier and more energetic while actually becoming unwell.
The encouraging news is that hyperthyroidism is usually very treatable. Depending on your cat's individual circumstances, options may include daily medication, a specially formulated prescription diet, radioactive iodine treatment or surgery.
Your vet will discuss the most suitable approach for your cat.
Urinary Tract Disease
Not every cat that drinks more has a hormonal or kidney problem.
Some urinary tract conditions can also make cats appear thirstier than usual.
These include:
Urinary tract infections.
Bladder inflammation (cystitis).
Kidney infections.
Bladder stones.
Although these conditions don't always cause excessive thirst, they often affect urination, which owners naturally notice first.
You may see your cat:
Visiting the litter tray repeatedly.
Passing only small amounts of urine.
Straining to urinate.
Crying while using the litter tray.
Passing blood in their urine.
Urinating outside the litter tray.
A Veterinary Emergency
If your male cat is repeatedly straining to urinate but producing little or no urine, this should always be treated as an emergency.
A blocked bladder can quickly become life-threatening and requires immediate veterinary treatment.
If you're ever unsure whether your cat is able to pass urine normally, don't wait to see if things improve. Contact your veterinary practice straight away.
Liver Disease
Although less common than kidney disease, diabetes or hyperthyroidism, liver disease can also lead to increased thirst in some cats.
The liver performs hundreds of vital functions, including processing nutrients, removing toxins and helping with digestion.
When it's not working properly, cats may develop a range of symptoms.
These may include:
Reduced appetite.
Weight loss.
Vomiting.
Lethargy.
Yellowing of the gums, eyes or skin (known as jaundice).
Increased thirst in some cases.
Because these signs are shared with several other illnesses, blood tests are often an important part of reaching a diagnosis.
Less Common Causes of Increased Thirst
While the conditions above are among the most common reasons for increased drinking, there are several other possibilities.
These include:
Certain medications, particularly steroids.
High calcium levels in the blood.
Some hormonal disorders.
Certain infections.
Less common kidney disorders.
This is one of the reasons we avoid making assumptions based on a single symptom.
Although searching online can be helpful, many different conditions can cause similar signs. A veterinary examination, together with appropriate tests, allows us to identify the underlying cause and recommend the most suitable treatment.
Could the Weather Be Responsible?
Yes, sometimes it can.
During warm summer weather, it's perfectly normal for many cats to drink a little more than usual.
Cats that spend time outdoors, enjoy sunbathing or live in particularly warm homes may naturally increase their water intake to stay hydrated.
Similarly, centrally heated homes during the winter can create a warm, dry environment that encourages some cats to drink a little more.
However, these changes are usually fairly modest.
If your cat suddenly develops excessive thirst, or the increase continues for several weeks, it's sensible to arrange a health check rather than assuming it's simply because of the weather.
Why Is My Cat Drinking from the Tap?
Many cats seem fascinated by running water.
Some prefer drinking from a dripping tap, while others wait patiently beside the sink until someone turns it on.
In most cases, this is completely normal.
Running water often tastes fresher, stays cooler and may simply be more appealing to some cats.
You can encourage healthy drinking habits by:
Providing several water bowls around the house.
Keeping bowls away from food and litter trays.
Refreshing water daily.
Using ceramic, stainless steel or glass bowls rather than plastic.
Trying a pet water fountain if your cat enjoys moving water.
A sudden interest in taps doesn't necessarily mean your cat is ill.
However, if it's accompanied by drinking noticeably more than usual, it may be worth arranging a veterinary check-up.
What If I Have More Than One Cat?
In multi-cat households, one of the biggest challenges is working out which cat is actually drinking more.
If you're concerned, you could try:
Offering separate water bowls in different locations.
Observing your cats at different times of day.
Monitoring litter tray habits if possible.
Feeding cats separately for a short period.
Using a water fountain for one cat and a bowl for another if they have different preferences.
Don't worry if you can't measure exactly how much each cat drinks.
Simply noticing that one of your cats seems to be spending much more time at the water bowl is valuable information to share with your vet.
What Happens During a Veterinary Consultation?
If you've noticed your cat drinking more water than usual, you may be wondering what will happen when you bring them to see us.
The first step is always to get to know your cat and understand exactly what changes you've observed. Even small details that might seem insignificant to you can provide valuable clues.
We'll begin by asking a few questions, such as:
When did you first notice your cat drinking more?
Has the change been gradual or sudden?
Is your cat eating normally?
Have they lost or gained weight?
Are they urinating more frequently?
Have you noticed any vomiting or diarrhoea?
Is your cat eating wet food, dry food or a combination of both?
Are they taking any medication?
Have there been any recent changes at home?
We'll then carry out a thorough physical examination. This includes checking your cat's weight, listening to their heart and lungs, assessing their hydration, feeling their abdomen and examining their coat, eyes and mouth.
Often, the combination of your observations and the clinical examination gives us a good indication of where to begin.
What Tests Might My Vet Recommend?
Depending on your cat's age, symptoms and examination findings, we may recommend further tests to help identify the underlying cause.
These commonly include:
Blood Tests
Blood tests allow us to assess how well your cat's organs are functioning and can help diagnose conditions such as:
Chronic Kidney Disease
Diabetes Mellitus
Hyperthyroidism
Liver disease
Changes in electrolyte levels
Modern blood testing provides a wealth of information and is often the quickest way to narrow down the possible causes of increased thirst.
Urine Tests
A urine sample can tell us just as much as a blood test in many situations.
It helps us assess:
How well the kidneys are concentrating urine.
Whether glucose is present.
Signs of infection.
Crystals or blood.
Evidence of inflammation.
Sometimes we may recommend sending the urine to a laboratory for bacterial culture if an infection is suspected.
Blood Pressure Measurement
Many owners are surprised to learn that we routinely measure blood pressure in older cats.
High blood pressure is particularly common in cats with kidney disease or hyperthyroidism and often develops without obvious symptoms.
Left untreated, it can affect the eyes, brain, heart and kidneys.
Fortunately, measuring blood pressure is quick, non-invasive and usually very well tolerated.
Imaging
In some cases, we may also recommend imaging such as ultrasound or X-rays.
These investigations allow us to look at the kidneys, bladder, liver and other abdominal organs in greater detail and can help us identify problems that aren't visible through blood or urine testing alone.
Every cat is different, so not every patient will need every test. We'll always discuss our recommendations with you and explain why they're appropriate for your cat.
How Can I Prepare for My Appointment?
There are several simple things you can do that will help us make the most of your visit.
Don't Restrict Your Cat's Water
If your cat seems thirsty, always allow them access to fresh drinking water.
It may be tempting to reduce how much they're drinking to see if it improves, but this can make some medical conditions worse and may leave your cat dehydrated.
Make a Note of Any Changes
Before your appointment, it can be helpful to write down:
When you first noticed the increased drinking.
Any changes in appetite.
Weight loss or weight gain.
Vomiting or diarrhoea.
Changes in energy levels.
Changes in litter tray habits.
Any medications or supplements your cat receives.
These details often help us build a clearer picture.
Bring a Urine Sample If Requested
If we ask you to bring a urine sample, try to collect one as fresh as possible on the day of the appointment.
Don't worry if you're unable to collect one. We can discuss alternative ways of obtaining a sample if necessary.
When Is Increased Thirst an Emergency?
Most cases of increased thirst aren't emergencies, but there are situations where your cat should be seen without delay.
Please contact a vet immediately if your cat:
Is straining to urinate but producing little or no urine.
Suddenly becomes very lethargic or collapses.
Stops eating for more than 24 hours.
Is vomiting repeatedly.
Has difficulty breathing.
Appears disorientated or has seizures.
Has severe weakness or is unable to stand.
If you're ever unsure, it's always safer to seek advice. We'd much rather reassure you than have you worrying unnecessarily at home.
The Importance of Senior Health Checks
Many of the conditions we've discussed become more common as cats get older.
One of the most valuable ways we can protect our senior cats is through regular health checks.
Cats age much faster than we do, and significant changes can occur within a relatively short period of time.
Routine examinations allow us to monitor:
Weight.
Body condition.
Blood pressure.
Kidney function.
Thyroid function.
General health and wellbeing.
Sometimes these checks identify changes before owners notice any symptoms at home, allowing treatment to begin at a much earlier stage.
For many cats, this early intervention can make a significant difference to both their quality and length of life.
Final Thoughts
Cats are wonderfully independent animals, but they're also experts at hiding when they're feeling unwell.
Often, the first clue that something has changed is surprisingly subtle. An empty water bowl that needs refilling more often, a larger clump in the litter tray or a sudden fascination with the kitchen tap may not seem important at first, but these small changes can provide valuable insight into your cat's health.
The reassuring news is that increased thirst doesn't always mean something serious. It may simply reflect warmer weather, a change in diet or your cat's individual preferences. However, because it can also be an early sign of conditions such as Chronic Kidney Disease, diabetes or hyperthyroidism, it's always worth paying attention.
As with many aspects of veterinary medicine, early diagnosis gives us the best opportunity to help. Many cats with these conditions continue to enjoy happy, comfortable lives for years with appropriate treatment and ongoing care.
If you've noticed your cat drinking more than usual, or if something simply doesn't feel quite right, trust your instincts. You know your cat better than anyone else.
At Roundwood Vets, we're here to support both you and your cat every step of the way. If you have any concerns about changes in your cat's drinking habits or overall health, please don't hesitate to get in touch. Our friendly team will be happy to answer your questions, examine your cat and help you decide on the most appropriate next steps.
After all, sometimes the smallest changes are the ones most worth noticing.
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