For hydro-jetting, separate the line, install a backflow preventer, begin with lower PSI, then increase as required
https://wiki-room.win/index.php/Dependable_Sewage-disposal_Tank_Emptying:_What_to_Get_Out_Of_Professional_Crews
For hydro-jetting, isolate the line, install a backflow preventer, start with lower PSI, then increase as needed, using proper nozzles to scour biofilm, roots, and scale without hurting pipes.