Why does my cat prefer running water?

A few things stack: movement catches a cat’s attention, running water is fresher than what’s been sitting in a bowl all day, and faucets and fountains often sit in open spots that feel safer to drink from than a corner crowded with food and litter. Preference varies a lot from cat to cat. In a controlled study of 12 indoor cats published in the Journal of Feline Medicine and Surgery, a fountain did not produce a meaningful increase in water intake or more dilute urine compared with a standard bowl. So if your cat loves the faucet, a fountain is worth trying. But bowl placement and wet food usually do more for hydration with less cost.

When to call a vet: if your cat is suddenly very interested in any moving water source and drinking much more overall, that increase deserves a vet visit.