You don’t need to scrounge up your manual as the valve settings for winterization are diagrammed on the unit itself. The control panel also contains the connection for the fresh water tank fill, the hookup for an outdoor shower (another is behind the passenger seat) and a water pump switch. Part of its functionality is shown in this Winnebago video.
On many class B camper vans the meter that measures your fresh water is shown in increments of a third. You’ll have an indication when you are full, two-thirds full, one-third full, and empty. The Solis features an old school manometer (a back-lit glass tube in the galley) that artistically and accurately measures the current amount of fresh water in your system.
When using hot water in your house, whether to take a shower, wash your hands, or wash the dishes., you turn on the hot water and watch cold water go down the drain as you wait for the water to get hot. In the process you waste water. This is particularly frustrating in a van when you only have 21 gallons of fresh water–you are wasting a precious resource. While you are waiting you are sending perfectly good fresh water into the gray tank. The Solis features an innovative feature that allows you to purge the cold water back into your fresh water tank. When you turn on the hot water faucet you get hot water.
As I mentioned it has a 21 gallon fresh water tank. The capacity of the gray water tank is 20 gallons and the cassette toilet holds 5.