Tote Tank Size
quote: I just have no idea of how quickly (for example) 22 gallons will fill up.
That is an issue that is very personal. If you take the same type of long hot shower that you do at home and both people do so every day, you will use your 22 gal. in one day. On the other hand, when we had a pop-up with a 10 gallon tank and no water heater, we could make that tank last for several days by washing in the sink with a half gallon of water and usint very carefully. With our previous motorhome, we used to go to square dance weekends where we would each shower every day in the "submarine" style and we could make a 40 gallon tank of water last for three days and have a little left. But if you do the same as when at home, it will probably need attention at least once each day, for two people and more often if there are more.
And to Steve, the size of tanks both for fresh water and for waste water and black water all vary quite widely. Generally the larger RVs have larger tanks, but that is not always true. There is no rule of thumb. Most RVs today have at least 20 gallons of waste tanks, but they could be less. And some have as much as 80 gallons. Keep in mind that you also need to have at least as much in fresh water as you do in waste, if dry camped. In a park with water & electric only, then you will need to be very careful of the volume in your blue tote tank, as it is not fun when the blue tank gets full before the on-board tank is empty!