Most cats drink less than their owners expect, and a bowl that sits full all day is the usual clue. Cats descend from desert animals and got most of their water from prey, so a dry-food diet plus a still bowl in the wrong spot is an easy way to end up with a cat that barely drinks. A few changes usually help. If you ever notice a sudden change in how much your cat drinks, in either direction, that's a vet question, not a bowl question.
Moving water wins
Many cats will ignore a bowl and then drink from a dripping tap. Running water looks fresher to them and is easier to see. This is the whole case for a fountain: a small pump keeps the water circulating and filtered, and a surprising number of "won't drink" cats start drinking the week one arrives. Quiet matters, because a pump that hums will keep some cats away. The Ceramic Automatic Fountain and the Golden Arc Ceramic Fountain are both built around a low-noise pump; the 1.8 L Circulating Fountain is the one to pick for a multi-cat home.
Move the water away from the food
Cats often avoid drinking right next to where they eat. Nobody is entirely sure why, but it is consistent enough to act on. Put the water in a different room from the food bowl, or at least a couple of metres away, and ideally somewhere calm with an open sightline.
Material changes the taste
Plastic bowls pick up scratches that hold bacteria and give water a flavour cats notice. Ceramic and stainless steel stay neutral. If you're sticking with a bowl, make it wide and shallow so the cat's whiskers don't press the sides, and wash it daily rather than topping it up.
More than one spot
Two water stations in different places usually get more total drinking than one big one, especially in a multi-cat home where one cat may be quietly guarding the bowl.
Wet food counts
If your cat eats mostly dry food, adding some wet food is the simplest way to raise water intake without the cat doing anything differently. A ceramic slow feeder like the Paw-Print Lick Mat makes wet food last longer, which some cats prefer.