[Snowman]

I thought I had a similar situation, but it turned out they just mislabeled the valves. The first trip out the shower started to back up, I went and pulled the valve for the greywater but it did not drain the shower. Went back closed the greywater valve and pulled the blackwater valve and it drained the shower (with clear water). Just to verify I hooked up the hose to the blacktank rinse and verified the tanks were plumbed correctly but the valves were mislabeled.