Our Airstream trailer was plumbed that way as is our new motor home. Others have pointed out cost benefits to the maker. I have always thought it was a benefit to me. In normal camping we have found our gray tank usually fills first by a whole bunch. I was glad to see some of it offloaded to the black tank.
Depending on the size and frequency of black tank deposits, your results may differ from ours.
Ken
Thor Forums
