I been doing al typs of pluming for over 10 years . I have my own problem I own a 7 family house for over 10 years. ,I would have to snake the draIn maybe every 18 months. now there was a laundry mat built right next door ,and now i have snaked it about 10 times in the last 2 years and 2 jets .I have a 4 in cast .I ask everybody and the aer lost.I thought that the laundry mat tyed int to my line .I thought the city was under sized , we found a ball of soap in the trap .MY basement is about 80 by 20 and in less the 24 hours (when cloged) the basement is fill about 3 in high plus out the leader to the street.(just think that is a lot of water for 7 family and no rain) I snaked it 12/19 and backing up again 12/29 .I video the drain after the blockage ,no sag no crack picth look good . ok I saw Richard cut out the main trap because there was some sort of problem alsoAllmy fixture are t****d also .I want to cut the trap out put to long sweep y s for clean out .I can not find if i can or cannot cut out the trap in the NYC plumbes code . I want to fix this problem and also save money about 250 everytime snake out and jetted is 850 .00 . If some one can help ,advice .if I over looked somethng. thank you