We will be camping with full hook ups for the first time in June. One of the rules of the campground states "please be sure you maintain a positive sewer seal at both ends of the sewer hose". Does this mean we just keep our tank valves closed until full and time to dump?

We mostly just drive to the mountains, pull off somewhere, and bookdock, so I'm not certain what this means. We will be staying in a campground in Livingston Montana. Can't wait as this will be a bucket-list trip for us.