I just did. Woo hoo... The bathroom sink is almost installed!
I'm not yet ready to do plumbing but am thinking of several options...
Option 1. I strap a 1 gallon holding tank to the ceiling where overhead storage would normally be. A pump tied into the solar panel pumps water directly to the holding tank. A float in the tank turns the pump off.
Option 2. Like option 1 but with a manual pump that includes somne form of overflow protection to indicate when the tank is full.
Option 3. Press a button and water is pumped directly from underbelly storage tanks.
Option 4. Like 3 but with a manual pump.
I like manual pumps because they don't need electricity. Don't know where to find them though.