Why Is My Cat Drinking So Much?

Call your vet now if

• Your cat is drinking much more and has also stopped eating or is eating far less
• There is repeated vomiting, or vomiting alongside the extra thirst
• Your cat seems weak, wobbly, unusually sleepy or hard to rouse
• You notice straining in the litter tray, producing little or no urine, or crying while trying to pass urine (this is an emergency, especially in male cats)
• Your cat may have had access to something toxic, such as antifreeze, lilies or human medicines
• Your cat is breathing fast, breathing with an open mouth, or has collapsed

If you are unsure whether something counts as urgent, ring your vet or an out-of-hours service and describe what you are seeing. They would always rather hear from you early.

Why a thirsty cat is worth noticing

Cats are descended from desert-dwelling ancestors who got most of their water from their prey. Many pet cats still have a fairly weak drive to drink, and it is common to hardly ever see them at the water bowl, particularly if they eat wet food. That is why a cat who suddenly seems to be drinking a lot stands out, and why it is worth paying attention to.

A noticeable rise in thirst is not a diagnosis in itself. It is a sign that something in the body may have changed. Sometimes the explanation is simple, such as a switch in diet or a hot spell. Sometimes it points to an underlying health problem that is much easier to manage when it is found early. Only your vet can tell the difference, usually with an examination and some straightforward tests.

Signs your cat may be drinking more

You do not need to measure every drop to notice a change. Common clues include:

• You are refilling the water bowl more often than you used to
• Your cat is visiting the bowl, tap, shower or even plant pots more frequently
• Clumps in the litter tray are larger, or there are more of them
• The litter needs changing sooner, or the tray seems wetter than normal
• Your cat is waiting by the sink or asking for water in a new way
• There are accidents outside the tray, which can happen when a cat needs to pass urine more often

Drinking more and urinating more usually go together. If you notice one, it is worth watching for the other.

Ordinary reasons for a change

Before worrying, it helps to think about anything that has changed in your cat's routine.

Wet versus dry food. Wet food is mostly water, so cats fed wet food often drink very little from the bowl. Cats on a dry diet need to make up the difference by drinking. If you have recently moved your cat from wet to dry food, or added more biscuits, you may see them drinking more, and that can be entirely expected. It still helps to tell your vet about the change if you are unsure.

Warm weather. Cats may drink a little more during hot spells or in a warm, centrally heated home.

Activity. A young cat who has been playing hard may drink more on some days than others.

A new water source. A water fountain or a fresh bowl in a new spot can tempt some cats to drink more. This is usually a good thing.

The key word is lasting. A day or two of extra drinking that settles down is rarely a concern. A change that carries on for more than a few days, or keeps creeping upwards, deserves a vet check.

What your vet may look at

When a cat is drinking more, vets commonly want to check how well the kidneys are working, whether the thyroid gland is behaving normally, and blood sugar levels. These are general areas of interest rather than a list of likely answers, and there are other possibilities too, including infections and hormonal or liver problems. Your vet will decide what is relevant for your cat.

Many of these conditions are more common in middle-aged and older cats, but younger cats can be affected too. Many are very manageable once identified, which is one of the best reasons not to wait and see for too long. You can read more about older cats in our guide to caring for a senior cat.

The visit will usually involve a physical examination, a weight check and questions about your cat's routine. Your vet may suggest a blood test and a urine sample. If you can, take note of anything else you have noticed, such as changes in appetite, coat or behaviour.

How to measure your cat's water intake at home

A simple record over a few days gives your vet useful information and helps you see whether the change is real.

1. Use one measured bowl. Pick up any extra bowls for a few days if you can, so all drinking water comes from one place.
2. Measure in and out. Fill the bowl with a known amount of water using a measuring jug. At the same time the next day, pour what is left back into the jug and note the difference.
3. Allow for evaporation. Put a second, identical bowl of water somewhere your cat cannot reach and measure how much it loses. Subtract this from the first figure.
4. Repeat for three to five days. Daily intake naturally varies, so an average over several days is more meaningful than a single reading.
5. Note the food. Write down what your cat ate each day, especially whether it was wet or dry food, as this affects how much they need to drink.

In multi-cat homes this is harder, as you cannot easily tell who drank what. Your vet can still use the overall figure, and they may suggest other ways to narrow it down.

For a sense of what is typical, see our guide to how much water a cat should drink. Keeping a simple log in Petopedia, alongside notes about food and litter, makes it easy to show your vet the trend rather than relying on memory.

What you can do in the meantime

• Always leave fresh, clean water available. Never restrict water to a cat who is drinking more, as they may need it.
• Keep the litter tray clean so you can spot changes in clump size and number.
• Watch your cat's appetite, weight and energy, and write down anything unusual.
• Avoid changing diet while you are waiting to see your vet, unless they advise it, so the picture stays clear.
• If your cat has lost weight as well, read why is my cat losing weight and mention it when you book.

When to book a routine appointment

Book a vet appointment within the next few days if your cat:

• Has been drinking noticeably more for more than a few days
• Is producing larger or more frequent litter clumps
• Is otherwise bright but just seems thirstier than before
• Is older and showing any change in drinking, eating or weight

If at any point the extra thirst is joined by vomiting, not eating, weight loss, weakness or lethargy, do not wait for the routine slot. Ring your vet that day. Our guide to signs your pet needs a vet can help you judge how quickly to act.

A thirsty cat is often a cat whose body is telling you something. Noticing it, measuring it and getting it checked are three of the kindest things you can do.