You fill your cat’s water bowl in the morning, and by lunchtime it is empty. Maybe you have noticed them lapping at the faucet or hovering over the bowl for longer than usual. It is easy to assume they are just thirsty, but when a cat starts drinking significantly more water than normal, it is often their way of telling you something is off inside their body. This behavior, called polydipsia, is a classic red flag for several health conditions. Let us walk through the most common reasons so you can figure out what might be going on with your cat.
1. Chronic Kidney Disease (CKD) is a Top Cause
Kidney disease is extremely common in older cats, and one of its earliest signs is increased thirst. As the kidneys lose their ability to concentrate urine, your cat loses more water through pee. To compensate, they drink more. If your cat is over seven years old and suddenly guzzling water, this is the first thing to discuss with your vet. Other signs include weight loss, poor coat quality, and vomiting. Managing CKD often involves a special diet and plenty of fresh water, so keeping an eye on their hydration is key.
2. Diabetes Mellitus in Cats
Just like in humans, diabetes in cats prevents their bodies from using glucose for energy. That extra sugar spills into their urine, dragging water along with it. This makes your cat pee more and, as a result, drink more to keep up. You might also notice your cat is losing weight even though they are eating normally, or that they seem more tired than usual. If your cat is overweight, their risk for diabetes is higher. A vet can run a simple blood and urine test to check.
3. Hyperthyroidism and Other Hormonal Issues
An overactive thyroid gland speeds up your cat’s entire metabolism. This can cause increased thirst, along with a ravenous appetite, weight loss, and hyperactivity. Hyperthyroidism is most common in middle-aged and older cats. Other less common hormonal causes include Cushing’s disease or a condition called acromegaly, but these are rarer. If your senior cat is drinking a lot but also seems wired and hungry, hyperthyroidism is a strong possibility.
“When your cat starts drinking more water than usual, it is not a quirk, it is a whisper from their body that something needs attention.”
4. Urinary Tract Issues and Infections
While not as common as kidney disease, a urinary tract infection (UTI) or bladder inflammation can also make a cat drink more. The infection irritates the bladder lining, making them feel like they need to pee constantly. To flush out the irritation, they may increase their water intake. If your cat is also straining to pee, going outside the box, or licking their genitals a lot, a UTI could be the culprit. These issues can be painful, so a vet visit is important. If your cat has a history of allergies, you might also notice other signs like sneezing or skin irritation, which you can read more about in our guide on why does my allergic cat sneeze so much.
5. Dietary and Environmental Factors
Sometimes the reason is simpler. If you recently switched your cat from wet food to dry kibble, they will naturally drink more because dry food contains very little moisture. A hot day, increased exercise, or a salty treat can also cause temporary thirst. But if the increased drinking lasts more than a day or two, do not assume it is just the food. Also, if your cat has food allergies, the inflammation from the allergic response can sometimes trigger increased thirst. Check our guide on signs of food allergies in cats to see if other symptoms match.
A healthy cat typically drinks about 4 ounces of water per 5 pounds of body weight per day. That is roughly half a cup for a 10-pound cat. If your cat is drinking more than a cup per 10 pounds, or if you are refilling the bowl way more often, it is time to take notice.
6. When to Call Your Vet
If your cat’s increased thirst lasts for more than 24 to 48 hours, or if it is paired with other symptoms like vomiting, diarrhea, lethargy, or changes in appetite, call your vet. They will likely want to run blood work, a urinalysis, and possibly a thyroid test. Catching conditions like kidney disease or diabetes early makes a huge difference in your cat’s quality of life. While you are waiting for the appointment, make sure fresh water is always available and consider adding a few extra bowls around the house. If your cat also has skin issues or itching, managing their allergies can sometimes help reduce overall inflammation, and you can learn more about how often to bathe a cat with allergies for comfort. And if you notice hairballs along with the increased drinking, it might be related to grooming changes, so check our guide on how often to brush a cat prone to hairballs.
