Cat Water Intake Calculator | How Much Should a Cat Drink?
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Introduction
Knowing how much water your cat should drink each day helps monitor and support their overall health and well-being. Too little could lead to dehydration, while drinking too much could indicate an underlying illness, such as chronic kidney disease or diabetes. But how much water should cats drink each day and have you considered the fluids they get from their food?
The cat water intake calculator can be used to estimate the following:
- Daily water requirement for your cat based on their body weight
- How much water they intake from their food
- Recommended amount of additional water they should drink
Also Read: Wet and Dry Cat Food Calculator | How Much Food Should I Feed My Cat?
Cat Water Intake Calculator
How Is the Required Daily Water Intake Calculated?
The calculation for daily water intake is based on the recommendation that the amount of water (ml) required is equivalent to the kilocalories (kcal) required per day,1, 2, 3 which in a healthy neutered cat is bodyweight (kg) x 30 + 70 x 1.2.
How Do I Find the Moisture Content (%) Of the Food?
The food's moisture content (amount of water) should be found as a percentage under the 'Guaranteed analysis' or 'Analytical Constituents' (on the packaging or the company's website). If you cannot find the moisture content enter '8' for dry cat food and '80' for wet cat food. Alternatively, you can contact the company that makes the food and ask them to provide you with the information.
How Is the Water to Drink per Day Calculated?
The water your cat receives from their food is subtracted from their required daily water intake to estimate the additional amount of water they should be drinking. Cats on a 100% wet diet have to drink a lot less water than those on a 100% dry diet, since wet food contains about 10x more water than dry food.
Is My Cat Drinking Enough Water?
To calculate how much water your cat drinks, measure the amount in their bowl at the start of a 24-hour period and how much is left at the end.
The amount of water can be measured in ml (using a measuring jug or large syringe) or grams (using digital weighing scales, since 1 g of water = 1 ml of water). Affordable and reliable scales like the Amazon Basics Kitchen Digital Scales work perfectly.
Since the amount of water your cat drinks each day may vary, consider recording the results for one week and taking an average.
Once you have performed your calculations, compare their 'Water Drank' to their recommended 'Water to Drink per Day'. We advise speaking to your veterinarian if you have concerns about the results.
How Much Water Should Cats Drink?
A healthy cat needs approximately 50-60ml of water per kg of body weight per day. For example, a 4.5 kg (~ 10 lb) cat should consume an estimated 225-270 ml of water daily, which is approximately 1 cup. However, the amount of water required will vary depending on their activity levels and ambient temperature, which increases in warmer climates and with higher activity levels.
How Many Times a Day Should a Cat Drink?
Typically, cats drink from their water bowl 2-4 times per day. However, cats who only eat wet food may not be seen drinking very often.
Why Is It Important to Monitor a Cat's Water Intake?
Cats have a low thirst drive and are not always the best at staying hydrated. This is because their ancestors evolved in the desert, where water is not always readily available, and their hydration needs were mostly met by eating small prey (typically containing 70–75 % moisture). As a result, they tend to respond to dehydration by producing highly concentrated urine to conserve water rather than drinking more.
However, staying hydrated is important for a cat's overall health since water is essential for regulating body temperature, lubricating joints and tissues, removing waste through the kidneys and stools, delivering nutrients and oxygen, and aiding brain function. Decreased water intake resulting in more concentrated urine is also a risk factor for bladder stones4 and idiopathic cystitis5 in cats. Therefore, ensuring your cat consumes enough water to stay hydrated is important for their general health and well-being.
Monitoring a cat's water consumption will also help you detect if they are drinking too much, which can indicate an underlying health condition.
Why Is My Cat Drinking a Lot of Water?
A cat may start drinking more water, such as frequent trips to their water bowl or prolonged drinking sessions, for the following reasons:
- A health condition, such as chronic kidney disease, diabetes, or hyperthyroidism
- They are losing water from vomiting, diarrhea, or lactating (producing milk)
- Due to hot weather or increased activity
- You switched from a wet diet to a dry diet
Polydipsia (excessive thirst) due to a medical condition is defined as a cat drinking more than 100 ml of water per kg of body weight daily, or more than 50 ml per kg if on a wet diet. For example, it would be concerning if a 5 kg cat on a dry diet drinks more than 500 ml of water a day, or a 5 kg cat on a wet diet drinks more than 250 ml of water a day. However, any changes in your cat's drinking behavior should be discussed with your vet.
When Should I Worry About My Cat Not Drinking Water?
If your cat is not drinking water, you should contact your veterinarian. Cats are very good at hiding that they don't feel well, so any changes in their behavior, however subtle, should be taken seriously. A cat who has stopped drinking water could be feeling nauseous, lethargic, painful, or distressed. The longer they go without drinking, the greater their risk of becoming dehydrated.
Is It Normal If My Cat Doesn't Drink Water but Eats Wet Food?
Cats fed wet food will drink less water than those only eating dry food since wet food contains approximately 80% moisture, compared to dry food, which is approximately 8% moisture. A cat on a 100% wet diet will receive most of their required daily water intake from their food. However, even though you may rarely notice them drinking, they must still have access to fresh water at all times.
Use the cat water calculator above to check if they are receiving enough fluid in their diet, and always contact your veterinary health care team if you are concerned, especially if they are showing other signs of ill health.
What Are the Signs of Dehydration in Cats?
Signs of dehydration in a cat include:
- Tacky/sticky gums (rather than moist)
- Loss of skin elasticity (when performing a skin pinch test)
- Sunken eyes
- Lethargy
- Reduced appetite
Checking for signs of dehydration is helpful but can be unreliable. For example, if a pet is mildly dehydrated, it may not be picked up on a physical examination. Also, older animals often have a positive pinch test since their skin is less elastic, so their skin does not spring back into place quickly, even though they may be well hydrated.
Dehydration could also be missed in an overweight cat. When their skin is pinched, it usually springs back into place quickly, even if dehydrated, due to the excess fat underneath. In addition, a nauseous cat may drool a lot, causing their gums to be moist, even though they could be dehydrated.
If there is a concern your pet may be dehydrated, they should be assessed by a vet, who can also perform bloodwork and a urinalysis to check for signs of dehydration.
How to Increase A Cat's Fluid Intake?
The best way for owners to ensure adequate fluid intake to keep their cats happy and healthy is to provide constant access to fresh, clean water. For additional ideas on improving your cat's hydration, such as the best water bowls, where to place them, using water fountains, and how to make flavored water, read How to Get a Cat to Drink More Water.
A wet diet is also a great way to increase a cat's water intake. However, as a veterinarian, I encountered many cats who refused wet food, so I put together my Top Tips on How to Get a Cat to Eat Wet Food.
References
- Bassert, J.M. et al. (2022) in McCurnin's clinical textbook for Veterinary technicians. St. Louis: Elsevier, p. 293.
- Case, L.P. (2011) in Canine and Feline Nutrition a resource for Companion Animal Professionals. Maryland Heights, MO: Mosby, p. 70.
- Wortinger, A. and Burns, K.M. (2015) in Nutrition and disease management for veterinary technicians and nurses. Ames, IA: John Wiley & Sons, Inc., p. 10.
- Bartges, J.W. (2016) "Feline Calcium Oxalate Urolithiasis: Risk Factors and Rational Treatment Approaches," Journal of Feline Medicine and Surgery, 18(9), pp. 712–722.
- Defauw, P.A.M. et al. (2011) "Risk Factors and Clinical Presentation of Cats With Feline Idiopathic Cystitis," Journal of Feline Medicine and Surgery, 13(12), pp. 967–975.
