To keep this pain away.
It sounds so easy now when I'm screwed because I didn't do so. So dear friends, really. Just take 8 glasses of clear water every day because you don't wanna experience this, believe me you. (and by 'this' I meant fever, antibiotics, ER and on top everything: THE pain)
So silly. All you have to do is: drink enough water.
Oh and toilet seat cleaner.