I think it's just for the toilet. The sink should be close enough to the galley gray tank to drain into it. I always have both black tank valves pulled out when I use the flush so I'm not sure on that one. Also there should be a sticker on the side of the trailer between the slides marking the black tank valve for the back bath.
__________________
2011 F350 Dually 13,300 GVWR 3.73 ratio
2013 WildCat 344QB with outside kitchen
|