twindman you are exactly correct, we learned this from Ozz, he figured it out and placed a flexible connection between black tank and "in-coming" waste line. We have not (so far) had a problem with our black tank cracking and leaking, but we travel empty or very near empty. However, we do have to occasionally move the Monty from the our Site to the Dump station at RV parks making the cracked and leaking tank a possible issue for us in the future.