How Much Water Should a Cat Drink? Hydration Guide
Cats are notoriously casual about drinking, which leaves many owners wondering whether their cat is getting enough water. It is a fair worry, because chronic under-hydration is closely linked to the urinary and kidney problems cats are so prone to. The good news is that the amount a cat needs is easy to estimate, the warning signs of dehydration are easy to spot, and there are several simple ways to encourage a reluctant drinker.
We have been helping Australian cat owners since 2018, and hydration is one of the most overlooked parts of cat care. Here is what you need to know about how much water your cat should drink, and how to help them drink more.
How much water should a cat drink?
As a general guide, a cat needs roughly 50ml of water per kilogram of body weight per day. For a typical 4kg cat that is around 200ml, and for a 5kg cat about 250ml, which is a little over a cup.
The crucial point is that this total includes the moisture in their food, not just what they lap from a bowl. That is why diet makes such a difference. Wet food is around 75 to 80 percent water, so a cat eating mostly wet food gets much of their daily requirement at mealtimes and will drink relatively little. Dry food contains only about 8 to 10 percent water, so a cat on kibble has to make up the shortfall by drinking far more. If your dry-fed cat barely touches the bowl, that is worth addressing.
Signs your cat is dehydrated
Knowing the signs of dehydration lets you act before it becomes serious. Look for:
- Lethargy and low energy:a dehydrated cat is often flat and less interested in play.
- Loss of appetite:dehydration and reduced eating tend to go hand in hand.
- Dry or tacky gums: healthy gums are moist and slick, while dehydrated gums feel sticky.
- Sunken eyes:the eyes can look dull or set back in the head.
- The skin-tent test:gently lift the skin at the scruff of the neck. It should spring straight back. If it stays tented or returns slowly, your cat is likely dehydrated.
- Reduced urination:fewer or smaller clumps in the litter tray.
If your cat shows several of these signs, or seems unwell, contact your vet, as moderate to severe dehydration needs prompt treatment.
Why cats don't drink enough
Cats descend from desert-dwelling wildcats and evolved to get most of their moisture from prey, so they have a naturally low thirst drive and often will not drink until they are already mildly dehydrated. Modern habits make it worse: a diet of dry food, a single bowl of still water that goes stale, or a bowl placed too close to the food or litter tray, which cats instinctively avoid. Some cats also dislike the way their whiskers brush the sides of a deep, narrow bowl.
How to get your cat to drink more water
A few easy changes make a real difference if your cat is not drinking water:
- Add a water fountain:most cats prefer moving water and drink more from a fountain than a still bowl. It is the single most effective change for many cats.
- Offer wet food: switching some or all of the diet to wet food dramatically increases water intake at the same time as feeding.
- Provide multiple water stations:place several bowls around the home, away from food and the litter tray.
- Use wide, shallow bowls:these avoid whisker fatigue and let your cat drink comfortably.
- Keep it fresh:change the water daily, as cats turn their noses up at anything stale.
- Try a splash of flavour:a little water from a tin of tuna in spring water, or a low-sodium pet broth, can tempt a fussy drinker.
When increased or decreased drinking means see a vet
A sudden change in drinking is a meaningful symptom in its own right. A cat that suddenly drinks far more than usual, and urinates more, may be showing early signs of kidney disease, diabetes or an overactive thyroid, all of which are common in older cats and need a vet check. At the other extreme, a cat that stops drinking and eating, or a male cat straining in the litter tray, can signal a urinary blockage, which is a genuine emergency. When in doubt, call your vet.
