You’ve been refilling your cat’s water bowl more often than usual. At first, you thought maybe the weather was warmer or you were imagining things. But now you’re certain—your cat is drinking significantly more water than she used to, and the litter box is heavier with wet clumps every time you clean it.
Increased thirst in cats isn’t something to dismiss. Unlike dogs, who drink frequently and enthusiastically, cats descended from desert animals and typically need relatively little water. When a cat suddenly starts drinking much more than normal, it usually means something has changed in her body’s ability to regulate fluids.
Diabetes is indeed one possible cause, but it’s far from the only explanation. Several common health conditions cause increased thirst, and recognizing the pattern helps you understand what might be happening and how urgently your cat needs veterinary care.
This guide explains what “drinking too much” actually means for cats, the medical conditions that cause excessive thirst, and the specific signs that help distinguish between different diagnoses.
What Excessive Water Drinking Looks Like
The medical term for excessive thirst is polydipsia, and it’s almost always accompanied by polyuria (excessive urination). These two symptoms go hand in hand because whatever drives your cat to drink more also causes her body to produce more urine.
Normal water intake for cats varies based on diet. Cats eating primarily wet food might drink very little because they get moisture from their meals. Cats on dry food diets need to drink more to compensate.
As a general guideline, cats typically drink about 3.5 to 4.5 ounces of water per 5 pounds of body weight daily. A 10-pound cat on dry food might drink around 7 to 9 ounces (roughly one cup) per day.
You’re seeing excessive drinking if:
- Your cat visits the water bowl much more frequently than before
- You’re refilling the water bowl twice as often as you used to
- Your cat drinks for noticeably longer periods at each visit
- She seeks out other water sources (dripping faucets, toilets, houseplant saucers)
- The litter box is saturated with large clumps of urine
- You’re scooping significantly larger amounts from the litter box
- Your cat urinates outside the box because she can’t make it in time
The key word here is “suddenly.” A gradual increase over months might not register as concerning, but cats with medical problems typically show a noticeable change over days to weeks. If you can pinpoint when the increased drinking started, that’s a sign the change is significant.
Seven Medical Conditions That Cause Increased Thirst
1. Diabetes Mellitus
Diabetes occurs when the pancreas doesn’t produce enough insulin or the body’s cells become resistant to insulin’s effects. Without proper insulin function, glucose (sugar) builds up in the bloodstream instead of entering cells for energy.
When blood glucose levels get too high, the kidneys try to remove the excess sugar through urine. This process pulls large amounts of water out of the body, creating excessive urination. Your cat then drinks more to replace the lost fluids, creating a cycle of drinking and urinating.
Other diabetes symptoms to watch for:
- Increased appetite (eating more but still losing weight)
- Weight loss despite good or increased food intake
- Weakness in the hind legs (walking flat-footed or on hocks)
- Poor coat condition
- Lethargy or decreased activity
- Sweet or fruity-smelling breath
Diabetes most commonly develops in overweight, middle-aged to older cats (typically over 7 years old). Male cats face slightly higher risk than females. Certain breeds like Burmese cats show increased susceptibility.
If caught early, some cats achieve diabetic remission with proper treatment, diet changes, and weight loss. However, this requires prompt diagnosis and careful management.
2. Chronic Kidney Disease
Kidney disease is extremely common in older cats. As kidneys deteriorate, they lose the ability to concentrate urine effectively. The damaged kidneys flush out more water than they should, and your cat must drink more to avoid dehydration.
Unlike diabetes, where the problem starts with too much glucose, kidney disease involves kidneys that simply can’t hold onto water and essential nutrients properly. They let too much water pass through into urine, along with proteins and other substances that should stay in the bloodstream.
Early kidney disease signs include:
- Gradually increasing thirst and urination
- Weight loss over weeks to months
- Decreased appetite or pickiness about food
- Occasional vomiting
- Bad breath (ammonia-like smell)
- Lethargy
Kidney disease progresses slowly in most cases. You might not notice the increased drinking immediately because it develops gradually over months. Many cats don’t show obvious symptoms until 70-75% of kidney function is already lost.
Senior cats (over 10 years old) should have kidney function tested regularly, as early detection allows for dietary management and medications that slow disease progression.
3. Hyperthyroidism
Hyperthyroidism happens when the thyroid gland produces excessive amounts of thyroid hormone. This hormone controls metabolism, so too much causes everything in your cat’s body to run on overdrive.
The increased metabolic rate creates more waste products that kidneys must filter, leading to increased urination and compensatory drinking. Additionally, the high metabolism generates more body heat, making your cat thirsty more often.
Hyperthyroidism symptoms often include:
- Increased appetite (often ravenous) but weight loss
- Hyperactivity, restlessness, or seeming “wired”
- Vomiting or diarrhea
- Poor coat quality despite increased grooming
- Rapid heart rate
- Increased vocalization
- Irritability or personality changes
This condition almost exclusively affects middle-aged to older cats (typically over 8 years old). It’s one of the most common hormonal disorders in cats and very treatable once diagnosed. Treatment options include medication, radioactive iodine therapy, or prescription diet.
Hyperthyroidism can feel dramatic because your cat’s personality might change noticeably. Previously calm cats become anxious and demanding. The constant hunger combined with weight loss is often what prompts owners to seek veterinary care.
4. Liver Disease
The liver performs hundreds of essential functions, including processing toxins, producing proteins, and managing nutrient metabolism. When liver function declines, various metabolic imbalances occur that can trigger increased thirst.
Liver disease causes increased drinking through several mechanisms: altered hormone processing, changes in how the body handles sodium and water, and the buildup of toxins that affect kidney function secondarily.
Liver disease warning signs:
- Yellowing of the skin, gums, or whites of the eyes (jaundice)
- Loss of appetite
- Vomiting
- Diarrhea
- Weight loss
- Abdominal swelling from fluid accumulation
- Increased urination and drinking
- Behavioral changes (seeming “out of it” or confused)
Liver disease has many potential causes: infections, toxins, certain medications, cancer, or inflammatory conditions. Unlike kidney disease which is extremely common in older cats, liver disease affects cats of all ages depending on the underlying cause.
The presence of jaundice (yellowing) is particularly significant. If you notice any yellow tint to your cat’s skin or eyes along with increased drinking, veterinary attention is urgent.
5. Urinary Tract Infection or Bladder Inflammation
Bladder infections aren’t as common in cats as in dogs, but they do occur, particularly in older cats or those with diabetes or kidney disease. Bladder inflammation (cystitis) can happen with or without infection.
When the bladder lining is inflamed or infected, it becomes irritated and sensitive. Your cat feels the urge to urinate frequently, even when the bladder isn’t full. She might also drink more because urinating frequently makes her thirsty, or because she’s learned that dilute urine is less painful to pass.
Bladder problem symptoms include:
- Frequent trips to the litter box with small urine amounts
- Straining to urinate
- Blood in the urine (pink or red-tinged)
- Urinating outside the litter box
- Crying or showing discomfort while urinating
- Excessive licking of the genital area
- Increased water drinking
Unlike systemic diseases where increased drinking and urinating are the primary symptoms, with bladder problems you’ll usually notice the litter box issues first. The increased drinking is secondary to the bladder discomfort and frequent urination.
Male cats with urinary symptoms need immediate veterinary care because they can develop life-threatening blockages that prevent urination entirely.
6. Pyometra (Uterine Infection in Unspayed Females)
Pyometra is a serious uterine infection that occurs in unspayed female cats, typically in middle-aged to older females. The uterus fills with pus, creating a severe infection that affects the entire body.
The infection causes increased drinking through several mechanisms: fever increases fluid needs, toxins from the infection affect kidney function, and the body tries to flush out the infection by producing more urine.
Pyometra symptoms include:
- Excessive thirst and urination
- Vaginal discharge (may be pus-like and foul-smelling, or absent in “closed” pyometra)
- Lethargy and depression
- Loss of appetite
- Vomiting
- Abdominal swelling or discomfort
- Fever
Pyometra is a medical emergency requiring immediate veterinary care and usually emergency surgery to remove the infected uterus. Without treatment, the infection becomes life-threatening within days.
This condition only affects unspayed females and typically develops weeks to months after a heat cycle. If your unspayed female cat suddenly starts drinking excessively, especially if she recently had a heat period, pyometra should be high on the list of concerns.
7. Medication Side Effects
Several common medications cause increased thirst and urination as a side effect. If your cat recently started a new medication and the increased drinking began around the same time, the drug might be responsible.
Medications that commonly cause increased thirst:
- Corticosteroids (prednisone, prednisolone)
- Diuretics (furosemide)
- Anti-seizure medications (phenobarbital)
- Some pain medications
Corticosteroids are particularly notorious for causing dramatic increases in drinking and urination. Cats on these medications might drink two to three times their normal amount. This is an expected side effect rather than a sign something is wrong, though it can be inconvenient.
If your cat is on medication and develops increased thirst, don’t stop the medication without consulting your veterinarian. Some drugs need to be tapered gradually rather than stopped abruptly. Your vet can assess whether the thirst is an acceptable side effect or whether medication adjustment is needed.
What You Can Do at Home
While increased thirst almost always warrants veterinary evaluation, you can gather helpful information before your appointment:
Measure actual water intake. For 24 to 48 hours, measure exactly how much water you put in the bowl and how much remains at the end of each day. This gives your veterinarian concrete numbers rather than subjective impressions.
Monitor litter box output. Note how many clumps you’re scooping and their size. Take photos if possible—this helps your vet understand the severity of the urination increase.
Check for other symptoms. Create a list of any other changes you’ve noticed: appetite, weight, energy level, behavior, vomiting, diarrhea, coat quality. These associated symptoms help narrow down possible causes.
Note the timeline. When did you first notice the increased drinking? Did it start suddenly or gradually? Has it gotten progressively worse? Did anything else change around the same time (new food, stress, medication)?
Ensure adequate water access. Never restrict water intake, even if the frequent refilling is inconvenient. Cats drinking excessively need that water to stay hydrated. Restricting access could cause dangerous dehydration.
Add extra litter boxes. If your cat is urinating more frequently, she might have accidents simply because she can’t make it to the box in time. Adding boxes in multiple locations prevents this stress for both you and your cat.
Don’t change the diet yet. Wait for veterinary diagnosis before making dietary changes. The appropriate diet depends on what’s causing the problem, and changing food now might complicate diagnosis.
When to See Your Veterinarian
Any cat drinking noticeably more than normal needs veterinary evaluation. This isn’t a symptom to monitor at home for weeks to see if it resolves on its own.
Schedule an appointment within 24 to 48 hours if:
- You’ve confirmed your cat is drinking significantly more than usual
- The increased drinking has continued for more than 2 to 3 days
- You notice larger or more frequent urine clumps in the litter box
- Your cat seems otherwise healthy but the drinking change is definite
Seek same-day veterinary care if:
- Increased drinking is accompanied by lethargy or weakness
- Your cat is also vomiting or has diarrhea
- You notice yellowing of the gums, skin, or eyes
- Your cat seems disoriented or confused
- She’s lost noticeable weight
- A male cat is straining to urinate or crying in the litter box
- An unspayed female shows vaginal discharge
Go to an emergency clinic immediately if:
- Your cat collapses or can’t stand
- She’s breathing rapidly or with difficulty
- Her gums are pale white instead of healthy pink
- A male cat cannot urinate at all (medical emergency)
- Your cat has a seizure
Your veterinarian will likely perform bloodwork (checking glucose, kidney values, liver enzymes, thyroid hormone), urinalysis (examining urine concentration and looking for infection or glucose), and possibly other tests based on initial findings.
Early diagnosis matters significantly. Diabetes, kidney disease, and hyperthyroidism all respond better to treatment when caught in early stages. Even serious conditions like pyometra have better outcomes with prompt intervention.
What to Expect at the Vet Visit
Understanding the diagnostic process helps you prepare for your appointment:
Your veterinarian will ask detailed questions about the drinking and urinating pattern, your cat’s diet, any recent changes in the household, medications, and other symptoms you’ve observed.
The physical exam checks weight, body condition, hydration status, heart rate, and whether any organs feel enlarged or abnormal. The vet will look for specific findings like thyroid enlargement, abdominal masses, or signs of dehydration despite increased drinking.
Common diagnostic tests include:
Bloodwork: Checks kidney values (BUN, creatinine), liver enzymes, glucose, electrolytes, and proteins. In cats over 7 years old, thyroid hormone (T4) is typically included.
Urinalysis: Examines urine concentration, presence of glucose or protein, signs of infection, and how well the kidneys are concentrating urine.
Blood pressure measurement: High blood pressure commonly accompanies kidney disease and hyperthyroidism.
Additional tests might include X-rays, ultrasound, or specialized bloodwork depending on what initial tests reveal.
Living With the Diagnosis
Many conditions causing increased thirst are manageable with appropriate treatment:
Diabetes requires insulin injections (usually twice daily), dietary changes to low-carbohydrate food, and regular glucose monitoring. Some cats achieve remission with early aggressive treatment.
Kidney disease treatment focuses on special renal diets, medications to manage blood pressure and phosphorus levels, and fluid support when needed. The goal is slowing progression and maintaining quality of life.
Hyperthyroidism responds well to medication (methimazole), radioactive iodine treatment, or prescription diet. Many cats return to completely normal once thyroid levels stabilize.
Urinary tract infections typically resolve with appropriate antibiotics, though underlying causes (like diabetes or kidney disease) need addressing to prevent recurrence.
The prognosis depends on the specific condition, how early it’s caught, and how well your cat responds to treatment. Many cats with these conditions live for years with good quality of life when properly managed.
The Bottom Line
Cats are naturally low-water-intake animals. When a cat suddenly starts drinking significantly more than her baseline amount, something has changed in her body’s fluid balance or kidney function. This isn’t normal variation or a quirk of personality—it’s a symptom that deserves investigation.
While increased thirst can signal serious conditions like diabetes or kidney disease, early diagnosis dramatically improves outcomes for all the common causes. The cats who do best are those whose owners notice the change early and seek veterinary care promptly.
Trust your observations. You know your cat’s normal habits better than anyone. If the water bowl needs refilling more often, if the litter box is heavier, if your cat seems constantly thirsty, those observations are valid and worth investigating.
Concerned about your cat’s drinking habits? Download our free Cat Symptom Checker to help you document symptoms and decide whether your cat needs immediate veterinary attention or if you can schedule a routine appointment. The guide includes a symptom tracker you can fill out and bring to your vet visit.