Cats are sneaky drinkers

Your cat strolls past the water bowl, ignores it completely, and you start to wonder: is she drinking enough? It is a fair worry, because cats are not big bowl-drinkers. Their ancestors lived in dry places and got most of their water from prey, which is roughly 70% water. A pet cat eating wet food still gets a lot of fluid from the dish, and may only visit the water bowl now and then.

The rule of thumb: about 50 ml per kg

A commonly quoted figure from veterinary nutrition sources is that a cat needs about 50 ml of water per kilogram of body weight per day. That is around 200 to 250 ml for a typical 4 to 5 kg cat. Some sources give a range of roughly 40 to 60 ml per kg, so treat 50 as a middle estimate, not a target to hit exactly.

That number is total water, and it includes the water inside food. Wet food is roughly 70 to 80% water (sources vary a little), while dry food is only about 10%. So the same cat can need very different amounts from the bowl depending on what is in the dish. Try it below.

Watch your own cat's normal, not the average. A sudden change in how much she drinks matters more than any number on this page.

How to tell if your cat is drinking more than usual

Measuring is easier than it sounds: fill the bowl with a known amount, and check what is left 24 hours later (keep other bowls and taps in mind). Write the number down. PDSA suggests bringing a note of how much your cat drinks in 24 hours if you ever need to see a vet about it.

Signs that she may be drinking more than she normally does include the bowl emptying faster than usual, drinking from places she normally ignores such as taps, sinks, the bath or the toilet, or drinking so much that she vomits. If you notice any of this, or any sudden change in drinking or toilet habits, ask your vet. Drinking more can be a sign that something is wrong, and only a vet can say what. This guide cannot tell you.

Small changes that get cats drinking

Cats Protection and other welfare groups share a few simple ideas that cost almost nothing:

• Keep water away from food and the litter tray. Cats seem to prefer water that is not right next to their dinner, and often in a different room.
• Offer several bowls in different places. Upstairs, downstairs, near a favourite window.
• Choose wide, shallow bowls so whiskers don't touch the sides. Ceramic, glass or metal is usually recommended over plastic, which can affect taste. Research suggests cats don't strongly favour one material, so go with whatever your cat uses.
• Keep it fresh. Change the water every day and wash the bowl. Some cats are fussy about chlorine, so filtered water may help.
• Add water to food. Wet food is the easiest way to raise a cat's water intake. If you change her diet, do it gradually, and ask your vet first if she has any health condition.
• Try moving water. Some cats love a running tap or a fountain. It is not a miracle: surveys of cat owners suggest most cats still drink from a bowl, so it is worth trying but never a must.

What to look for in a cat fountain

If you decide to try one, a few things matter at any budget:

• Easy to clean. A fountain that is a pain to take apart will be skipped, and a dirty fountain is worse than a bowl. Look for parts you can rinse by hand.
• A decent filter you can replace, plus a clear idea of how often you will need new ones.
• Quiet running. Cats can be put off by a humming pump. A low-noise or interval mode helps.
• Enough capacity and a visible water level, so it never quietly runs dry.

Also keep the cord out of reach of chewers, and keep the old bowl out for a week or two while she gets used to the new thing.

Sources

• Royal Canin Veterinary Academy: water requirements and drinking habits of cats
• Cats Protection: cats and drinking
• PDSA: is my cat drinking and weeing too much?

Sources differ slightly on how much water wet food contains (about 70 to 80%), which is why the calculator is an estimate.