Why your pet drinks water strangely — and when to worry.

Pets drink water in ways that seem peculiar to us and are rarely peculiar to them. A cat who will ignore a freshly-filled bowl but drink enthusiastically from the bathroom sink. A dog who will only drink from the toilet. A cat who paws at the surface of the water before drinking. A dog who laps once, pauses, then starts again.

Most of these are normal, explainable, and not cause for concern. A few are not.

Here is a guide to telling them apart — what's a quirk, what's a preference, and what's worth raising at the next vet visit.

The dripping-tap preference

Cats especially, but also many dogs, will prefer moving water over still water. A bathroom sink running briefly, a shower head dripping after use, a garden hose trickling into a plant pot — these are often more attractive than a full bowl of clean water two metres away.

The explanation is largely evolutionary. In the wild, still water is stagnant water, and stagnant water is more likely to be contaminated with bacteria or parasites. Moving water signals freshness. Domestic cats retained this preference more strongly than dogs, which is why fountains tend to work better for cats than for dogs in terms of encouraging hydration.

This is not a problem. It is a preference, and one you can honour by either keeping a small fountain for the animal, leaving a specific tap dripping at cat height during the day, or simply accepting that the animal will ignore the bowl in favour of the sink and planning the sink visits into the household rhythm.

Pawing at the bowl

Cats sometimes paw at the surface of the water before drinking. They may also pull water toward their mouth with a paw rather than dipping their face into the bowl. To a first-time cat owner this looks alarming — is the water wrong? is the cat confused? — but the behaviour has straightforward explanations.

Cats do not see still water well. Their vision is tuned for movement detection, and a motionless reflective surface sits in a visual blind spot where the edge of the water can be hard to locate. Pawing at the surface is the cat creating ripples so it can see where the water actually is. Pulling water with a paw is a variation of the same problem — the cat is using tactile information to locate a surface it can't see clearly.

Use a wider, shallower bowl so the water surface is closer to flush with the rim. Keep the bowl filled high. Both make the water easier for the cat to see and drink without the paw routine.

Ignoring fresh water for puddles

Dogs, particularly ones with access to a garden, will often pass over their own bowl in favour of a puddle after rain. This is not a statement about your water. It is a combination of three things: the puddle is cooler (ground temperature rather than room temperature), the puddle has new smells from the environment, and the dog is outside anyway so drinking there is convenient.

Most puddles are harmless. Puddles in areas treated with road salt, pesticides, antifreeze, or fertiliser runoff are not. In suburban or urban gardens with driveways, be cautious about standing water near areas that get chemical treatment. Covered or shallow drinking stations outside, placed away from chemically-treated zones, solve this without fighting the preference.

Sudden increase in drinking

This is the one to watch. A pet that begins drinking substantially more water than usual — refilling a bowl two or three times in a day when it used to take two days to drain — is giving you information about its health.

The most common causes of persistent increased thirst (polydipsia) in dogs and cats are diabetes, kidney dysfunction, Cushing's disease, and urinary tract infections. All four are manageable if caught early. None of them are visible to the eye; they are visible in the water bowl.

Temporary increases in drinking — after a long walk in heat, after a salty meal, after recovery from vomiting — are expected and resolve within a day. Sustained increases over a week are not normal and warrant a vet visit. If you can, estimate the volume (litres per day, roughly) before the appointment; it helps the clinician.

Sudden decrease in drinking

Equally important, and often missed because it is a negative signal. A pet that stops drinking as much as usual may be in pain (dental, urinary, gastric), may have nausea, or may have reduced mobility that makes the bowl harder to reach.

Some decreases are benign. A pet on a new wet-food diet will drink less from the bowl because they are getting more moisture from the food. A cat that has found a new water source you haven't noticed (a leaking garden hose, for instance) may be drinking there. A change in weather from summer to autumn reduces fluid needs naturally.

The test: check hydration directly. Gently pinch the skin at the scruff of the neck. In a hydrated pet it springs back immediately. In a dehydrated pet it returns slowly or stays tented briefly. Check gum colour — pink and moist is normal, pale or tacky is not. If those signs are off and the reduced drinking has persisted more than twenty-four hours, go to the vet.

The broader principle: the water bowl is a diagnostic instrument. Most of what it shows is normal quirk. Some of what it shows is early warning. The owner who pays quiet attention to it catches problems weeks earlier than the owner who only notices when the pet seems visibly unwell.