People ask how much do cats drink? I am confining this discussion to domestic cats but obviously the amount that cats drink depends upon the species of cat. With respect to domestic cats the amount that they drink also varies depending upon their circumstances so you’ll have to read this post to get the answer. There is no instant answer as it is too complicated. There are some useful links to articles below this one, incidentally.
The water intake of a domestic cat essentially comes from (a) drinking water and (b) the water present in the food that they eat. There is a third source which I won’t discuss here namely metabolic water which is produced during the assimilation of food.
The amount of water in their food depends upon whether it is wet or dry. Commercial dry food contains 7% to 12% water. Wet food contains up to 78% water. When a cat is fed wet cat food their voluntary water intake can be very low because their water requirement is included in the food that they eat.
A lot of domestic cats are fed a convenient (for the person) dry food diet and therefore there is a much greater demand upon the cat to voluntarily drink water. It is said that domestic cats don’t compensate for a dry diet by drinking enough water. This leaves them, arguably, in a permanent state of slight dehydration which can lead to urinary tract issues.
Other factors affecting a domestic cats voluntary intake of water include environmental temperature, their activity level and their general health and psychological state. The cat’s age is also a factor. Another factor is whether a female cat is lactating as she will require more water under these circumstances.
The amount of water intake is also affected by energy intake. The higher the energy intake the higher the metabolic waste production and the heat produced by nutrient metabolism. The body requires more water to excrete waste products.
Linda P Case, in her helpful book, The Cat Its Behaviour, Nutrition and Health at page 297 tells us that an adult domestic cat’s water requirement can be based upon the number of kilocalories of energy consumed by the cat per day. A 10 pound (4.5 kg) domestic cat with a daily energy requirement of 360 kcal requires about 360 mL of water per day (mL = milliliters). This is 12.7 ounces. This sounds like a lot but if your cat is eating canned wet food he will obtain almost all his water needs from his food. Also I suspect that most domestic cats expend less energy than this especially if they are full-time indoor cats.
At the opposite end of the spectrum, the domestic cat fed solely on dry cat food pellets would need to take in almost all his water by drinking water. A minimum of 150 ml per day has been recommended when on this diet.
My personal experience is that my cat drinks quite a lot less than the amount stated. He eats dry and wet cat food. I don’t measure the amount he drinks because healthy cats are able to self regulate water intake. Personally, I would not take it as read that domestic cats are able to self regulate water intake entirely properly and accurately if they are solely fed on dry cat food. This is because dry cat food is unnatural and, in my view, it makes it more difficult for a cat to self regulate.
The domestic cat’s wildcat ancestor is the North African Wildcat as you probably know. Their natural diet would be rodents such as mice. Mice contain 70% water. So the natural, innate assessment of the domestic cat is based upon a presumption that they are eating mice. They have to make a particular reassessment in order to accommodate the fact that the eating dry cat food. That’s why I have stated that they may under consume water if fed on exclusively dry cat food.
I’m going not going into veterinary topics in this article but if a cat is drinking a lot of water, much more than specified on this page, it is likely that the cat is suffering from kidney disease. You should consult with a veterinarian. There will also be increased urination. This is called polydipsia and polyuria.