My cat has a thick coat and sheds a lot. When she cleans herself, she gets hair in her system. So we do the following:
brush her feed her Science Diet Hairball control food give her Laxaire (that brown lubricant) once in a while make sure she gets water
With cats, it pays to notice how they like their water. My previous cat liked it best straight from the bathtub - a tiny stream absolutely fresh and cold.
The present cat likes to drink in my bedroom just before retiring. There's a stainless steel bowl next to the hamper which I fill every night. She knows that I am right there to fend off any timberwolves, so she feels safe as she drinks.