Most cat owners wonder at some point whether their cat would be better on wet food or kibble. It is one of the questions vets hear most often, and it has no simple answer. Both can feed a cat well, and plenty of cats live long, healthy lives on either. Where the two formats differ is in the extras. Wet food happens to carry a lot of water, and that turns out to matter more to a cat's health than you might expect.

The Hydration Difference

The Hydration Difference

Wet food is around three quarters water. Kibble is nearer one part in ten. That gap matters because cats aren't good drinkers. Their wild ancestors got most of their water from the prey they ate, and modern cats still tend to treat the water bowl as an afterthought.

Researchers at the Waltham pet nutrition centre in Leicestershire tested this with six cats. They fed them the same food at four moisture levels, from bone dry up to 73 percent water. Cats on the drier food did drink more from the bowl, but nowhere near enough to make up the difference. On the wettest food, the cats took in about 40 percent more water in total. Their urine was more dilute, and the chemistry that leads to calcium oxalate stones moved close to the safe zone.

Dilute urine is the main reason vets suggest wet food for cats who have had urinary trouble. Good hydration also helps the kidneys, which matters more and more as a cat gets older.

The water in wet food does something else too. It takes up room in the stomach, and a team in California found that changes how much a cat eats...

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Research rating: ⭐⭐⭐⭐ (4 of 5). Last updated 25 August 2026.

Sources

  • Buckley CMF, Hawthorne A, Colyer A, Stevenson AE. Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat. https://doi.org/10.1017/S0007114511001875
  • Bermingham EN, Young W, Kittelmann S, Kerr KR, Swanson KS, Roy NC, Thomas DG. Post-Weaning Diet Affects Faecal Microbial Composition but Not Selected Adipose Gene Expression in the Cat (Felis catus). https://doi.org/10.1371/journal.pone.0080992
  • Wei A, Fascetti AJ, Liu C, Villaverde C, Green AS, Manzanilla EG, Havel PJ, Ramsey JJ. Effect of water content in a canned food on voluntary food intake and body weight in cats. https://doi.org/10.2460/ajvr.72.7.918