How much water should a dog drink?
This guide is general information and not a substitute for your veterinarian. For your own dog, your vet is always the right person to ask.
The water bowl is empty again, and you can't remember whether it always went this fast. The short version: a healthy dog drinks roughly 40 to 60 millilitres per kilogram of body weight a day, about 1 to 1.8 fluid ounces per pound. A 20 kg dog lands somewhere around 0.8 to 1.2 litres. Once a dog is consistently over about 100 ml per kilogram a day, vets call that increased thirst, and it's worth investigating.
The trouble with this question is almost always the same. You have a feeling it's gone up, but you don't have a number. Below is how to measure it properly over a few days, where the line sits, what can be behind it, and what to do with the result at the vet. There's a log you can print, too. Cats work differently, and their numbers are further down.
How much water should my dog drink a day?
The usual rule of thumb is 40 to 60 millilitres per kilogram of body weight over 24 hours. Roughly translated:
- 5 kg (11 lb): about 200 to 300 ml a day.
- 10 kg (22 lb): about 400 to 600 ml.
- 20 kg (44 lb): about 0.8 to 1.2 litres.
- 35 kg (77 lb): about 1.4 to 2.1 litres.
Those figures assume a dog eating dry food. If yours is on wet food and barely touches the bowl, that's fine. Wet food is roughly three quarters water, so a lot of the daily requirement arrives in the food bowl rather than the water bowl. Switch a dog from wet to dry and you'll watch the drinking go up without anything being wrong.
Single high days are normal too: heat, a long walk, excitement, a salty chew, or a season. What counts isn't one day. It's whether the number stays up across a week.
When is it too much?
The veterinary line sits at about 100 millilitres per kilogram of body weight a day. A dog who stays above that for several days is drinking more than expected, which vets call polydipsia. For a 20 kg dog that's more than 2 litres daily. For a 10 kg dog, more than 1 litre.
The change matters just as much as the threshold. A dog who sat at 700 ml for a year and now sits steadily at 1.4 litres has doubled, even though he never crosses the 100 ml line. That jump is worth an appointment, and it only shows up for someone who has the earlier number.
Increased thirst on its own usually isn't an emergency. It's a "measure it for a few days, then book a visit" thing, not a reason to drive to the clinic at midnight. Do call your vet promptly though if any of these come with it:
- The thirst jumped suddenly and dramatically, over days rather than months.
- Your dog is vomiting, has gone off food, or seems flat and tired.
- He's losing weight while eating normally or even more than usual.
- He's suddenly having accidents indoors, or needing to go out at night when he never did before.
- A puppy or young dog has become noticeably thirsty.
Staying calm never means downplaying the danger. Those combinations are the difference between "in the next couple of weeks" and "this week".
How to measure your dog's water intake
All you need is a measuring jug and a piece of paper. The whole trick is that every drop of water going into the bowl gets measured on the way in.
- Measure and write it down in the morning. Fill the bowl with a known amount, say 1000 ml, and note it.
- Only top up with measured amounts. If the bowl empties during the day, add another measured amount and note that beside it. You'll add them all up at the end.
- Measure what's left after 24 hours. At the same time next morning, pour whatever remains back into the jug. Total poured in, minus what's left, is what your dog drank.
- Account for every water source. A second bowl in the garden, the other dog's bowl, the toilet, a water butt, puddles on walks. If you can't control all of them, note that honestly rather than abandoning the measurement.
- Do three to seven days in a row. One day tells you almost nothing. Only the run shows whether the number is genuinely high.
Two things make the number far more useful. Write down your dog's weight, because without it nobody can convert the volume into millilitres per kilogram. And write down what he eats. The same 1.5 litres means something different on dry food than on wet. In a multi-dog house, separating them at drinking time for the measuring days is a nuisance, but it's the only way to know whose water it was.
What can be behind increased thirst
First, so the list below doesn't read worse than it is: the most common reasons for an empty bowl are harmless. Heat, more exercise, a food change, salty treats. It only gets medically interesting once you've ruled those out and the number stays up for days.
When your vet does start looking, these are among the more common causes. This isn't a diagnosis and it isn't a ranking for your dog. It's just why the blood test comes next:
- Kidney disease. Damaged kidneys can't concentrate urine properly, so more water is lost and the dog drinks to keep up. Increased thirst is often the first visible sign. There's more in our guide to chronic kidney disease in dogs and cats.
- Diabetes. When blood sugar runs high, sugar spills into the urine and pulls water with it. The classic picture is drinking more, urinating more, and losing weight despite a good appetite. Daily life with it is covered in our guide to diabetes in pets.
- Cushing's disease. Too much of the body's own cortisol, mostly in older dogs. Increased thirst is often the thing owners notice first, usually alongside panting, a rounder belly, and a thinner coat. If the diagnosis is already in, our guide to what to track with Cushing's disease covers what matters between rechecks.
- Medications. Steroids and some diuretics raise thirst as a known side effect. If your dog has started something new, say so at the appointment.
- Womb infection in unspayed females. Increased thirst a few weeks after a season, often with lethargy or discharge, is a reason to phone rather than wait and see.
Which one it is doesn't get decided at the water bowl. It gets decided with blood and urine tests. That's exactly why your measurements are useful: they answer the first question your vet asks before the search even starts.
How much water should a cat drink?
Cats run lower, and the margin is tighter. Around 40 to 60 millilitres per kilogram a day including food is the usual guide, and plenty of cats on wet food barely drink from the bowl at all. That's what makes a change so noticeable. A cat who suddenly waits at the tap, drinks from flower vases, or whose bowl needs refilling for the first time in years is worth an appointment.
In cats this pattern points at kidney disease or diabetes particularly often, and both start quietly. If you already know kidneys are the issue for your cat, our guide to hydration strategies for CKD pets covers how to get more water in and what to track while you do. One more signal worth watching alongside drinking: the litter tray. Bigger or more frequent urine clumps are the same information seen from the other end.
What your vet will want from you
An appointment about thirst goes better when you bring four things. You don't need to remember any of it, because it's on your sheet:
- The measured intake in millilitres per day, across several days.
- Your dog's current weight, and the weight from a few months ago if you have it.
- What he eats, dry or wet, and whether that's changed recently.
- When you first noticed, and what else has changed: urine volume, appetite, coat, energy, needing out at night.
There's a real gap between "he's been drinking a bit more lately" and "he's been on 2.1 litres a day for six days, at 19 kg, on dry food". The second sentence is a starting point for an investigation. The first is a hunch your vet has to go and verify. Keep logging afterwards too, because once treatment starts, water intake is often one of the first things that shows whether it's working.
Notebook, spreadsheet, or app?
The honest answer: the best method is the one you'll actually keep up. For a single measuring week, the simplest option is plenty.
- A sheet on the fridge sits right by the water bowl and needs no battery. Our printable water intake log has rows for the date, amount poured in, amount left, the total drunk, and the food type, plus the per-kilogram conversion.
- A spreadsheet works out millilitres per kilogram for you and shows the trend as a line.
- An app can remind you to do the evening measurement and keep the numbers together for the vet visit.
That's what we're building Felova for, an app that reminds you about measurements and medications and keeps the numbers in one place for your vet. It's not out yet. You can join the waitlist, and until then a sheet on the fridge does the same honest work. What matters is that by the end of the week you have numbers rather than an impression.
Common questions
My dog is drinking a lot but seems fine otherwise. Do I still need the vet?
Measure it first. If he's clearly above the rule of thumb across several days, or the amount has changed a lot from before, then yes, that's worth an appointment even though he seems well. Kidney and hormonal conditions often start exactly like this: the bowl is the first thing that changes, and the dog still feels great.
Does water in the food count?
Toward the daily requirement, yes. Toward your measurement, no. You're only measuring what leaves the bowl. That's why you note whether your dog is on dry or wet food alongside it, so your vet can factor it in when reading the number.
Could heat alone explain a number this high?
Dogs drink noticeably more in hot weather and after hard exercise, and that's normal. The difference is how long it lasts. Heat-driven drinking settles when the heat does. If the number stays up on cool, quiet days too, heat isn't the explanation.
Should I limit water if my dog is drinking too much?
No. Taking water away doesn't treat the cause. It removes the dog's way of compensating for a loss he can't control, and it can dehydrate him seriously. Water stays freely available. The thing you change isn't the bowl, it's that you measure the amount and take it to your vet.
Felova is being built for exactly this kind of tracking, a calm place for numbers like water intake, weight, and medication so the trend is there when your vet needs it. It's not out yet.
Join the waitlist →