Depends on what you want to say, since "Tomar' has two meanings. "Tomar", as in drinking and "tomar", as in taking.
I honestly don't think there's actually a formal way of saying tomar. It depends on the sentence & how you want to address the person. Ex. Usted se puede tomar el agua? Can you drink the water? Ahora, ustedes tomaran el examen > Now, you'll take the exam (but in a polite way!)
