For hydro-jetting, separate the line, install a backflow preventer, start with lower PSI, then increase as needed

https://wiki-global.win/index.php/Sewage-disposal_Tank_Pumping_and_Setup:_Cost-Effective_Solutions_You_Can_Trust_28657

For hydro-jetting, separate the line, install a backflow preventer, begin with lower PSI, then increase as required, using suitable nozzles to scour biofilm, roots, and scale without hurting pipes.