The instructors are employed by Camping World as Good Will representatives. Most of us starting camping in a tent, with no facilities whatsoever. This reflects the fact there's a lot of sales revenue related to septic sales. All self contained RVs have black and gray water systems.
Capacities vary across the lot, with larger RVs typically having larger tanks.
If you're boondocking the rule of thumb is that whatever the capacity of your holding tanks, it won't be enough. But you will find creative ways to minimize fresh water usage, and waste tank use. Examples include use of paper plates. And even when you do dishes, heat water on the stove to avoid running fresh water until the hot water shows up at the tap. All of the tanks have vents.