I've got a 42 gallon blue tote, bought it for a 10 day stay at the beach with water but no sewer and only had 15 gallon tanks at the time. Since then I've only used it twice, but I'm thinking of using it at home since my trailer is my home office. I'll empty the black tank every few weeks into the septic system. I'd get a macerator to do it but I've already got the blue tank so might as well use it.
As far as fresh water, we carry 2x 5 gallon collapsible jugs, we use them going to Florida and coming back when the trailer is winterized, we've also used them to fetch water when there's a mains issue, a nearby store is on a different water system and I can fill 5 gallons there for under $1.
