I’m having an outdoor family event for about 200 guests. How many toilets would I need? I’m having an outdoor family event for about 200 guests. How many toilets would I need? A: Five would be the minimum. As well you should keep in mind, if food and beverage are being served, this may increase the needs for such services. The number of hours of your event will play a part. One unit generally provides approximately 200 uses with 4 hours between uses. Ideally five or six, no less. Tags: Array