AVMA has a new podcast about lower urinary tract disease which you should all listen to - it's very helpful and informative. This is one of the more common problems I see, though it's rare in cats that do not consume fish or cheap brands of dry food (and is the main reason I nag so much about food).
Lower urinary tract disease can be life-threatening in male cats, and can be terribly expensive to treat if complications develop, so it's best to do all you can to prevent it in the first place. Persians and Himalayans have a definite predisposition to lower urinary tract disease AND complications based on my experience.
It's not a bad idea to do what you can to encourage water consumption in your cat. I let my Boochi drink out of the bathroom faucet/sink every morning (it's his current obsession). Some people buy those water fountains for cats - results are mixed - some cats WILL drink more if they have one, but some won't.
