Cats drank 27.5 mL per kg a day from a still bowl and 26.1 from a fountain: a fountain is a preference, not a hydration fix
Teo Varga, Pet tech editor (AI-assisted) · · updated
Pet fountains are often sold on one promise: cats drink more from moving water. It is a reasonable guess about an animal that often seems to ignore its bowl. When researchers measured it carefully, though, the bowl type made no real difference.
What the study measured
Michael Robbins and colleagues gave 16 healthy laboratory cats, of which 14 completed the study, each of three bowls in turn: a still bowl, a circulating bowl and a free-falling one [2]. Each bowl had a week to get used to, then 14 days of measurement [2]. Intake was weighed daily, corrected for evaporation with a sham bowl and for spills with an absorbent mat [2].
The averages were close [2]:
| Bowl [2] | Water a day, mL per kg [2] | For a 4 kg cat [1] |
|---|---|---|
| Still | 27.5 | 110 mL |
| Circulating | 26.3 | 105 mL |
| Free-falling | 26.1 | 105 mL |
The authors concluded that "overall, water bowl type had no appreciable effect on water intake" [2]. Urine volume and concentration did not differ either, except one measure, osmolality, which was higher with the circulating bowl and whose meaning the authors called unclear [2]. They also describe an earlier study of 13 cats that compared a still bowl with a free-falling one and found no statistical difference in intake [2].
Why some owners still see a difference
Averages hide individual cats. Three of the 14 cats did show a preference: one drank more from the circulating bowl, one from the free-falling bowl, and one from the plain still bowl [2]. Cats also differed a lot from one another: the spread between cats was about a fifth of the average [1] [2]. So an owner who sees their cat drink more from a fountain may be right about that cat. The study only says that, on average, the moving water itself does not make cats drink more.
- Your cat's weight: 4 kg
- Water a day per kg: 27.5 mL
- Days away: 2 days
Works out: Water a day; Water for the days away; With a full spare bowl's margin, at least
What the study suggests does matter: the food
Every cat in the study ate the same dry kibble, with 6% moisture, so the bowl was nearly its only source of water [2]. The figures above describe dry-fed cats. Kibble is under 10% water and most canned or moist food about 80%, and the authors list feeding high-moisture food among the ways to increase a cat's water intake [2]. A cat on wet food takes in much of its water with its meals, so it will likely drink less from the bowl than these figures, and that alone is no sign it is drinking too little; if you are worried about a cat's intake, the food is the first thing to discuss with your vet.
Nerd corner
The study used a 3 × 3 crossover: every cat had every bowl, in a randomised order, so each cat served as its own control [2]. With the still bowl the standard deviation was 5.8 mL per kg a day, about 21% of the mean [1] [2]. Against that spread, the 1.3 mL per kg a day between still and flowing bowls is small [1]. The cats were healthy adults in a controlled colony. Cats with kidney disease, or very young or old cats, were not tested [2].
Check yourself
About how much does a 5 kg cat drink in a day? About 130 to 140 mL, at 26 to 27.5 mL per kg [1] [2].
Did any cat prefer a bowl? Yes, three of 14, and one of them preferred the plain still bowl [2].
What did the authors suggest for cats that need more water? Other ways than the bowl type, since the bowl made no appreciable difference [2].
General information, not veterinary advice. A notebook entry for smartpethome.xyz, written with AI. The study figures are quoted from the paper; the per-cat amounts are computed from them.
*Corrected 2026-11-06: The study's cats ate dry food only, which the figures depend on; the 21% spread is between cats, not day to day; the earlier 13-cat study is not described as in homes.*
*Corrected 2026-11-08: Source 1 pointed at the site's home page, so the registry held no sources. The study's figures were checked against the paper (27.483, 26.327, 26.137 mL/kg/day; spread 5.847; P = 0.942; three cats with a preference; 6% moisture kibble) and the per-cat amounts are now the site's data page, computed from the exact means two ways, and linked. The study enrolled 16 cats, of which 14 completed. The closing note said 'checked by hand'; nothing records a person did, so that claim is removed. The title carries the figures. Headline was: "Do cats drink more from a fountain? Measured, it made no difference".*