Hi. I am replacing the old cast iron drain pipes with pvc pipes but the connection to the main sewer from my house is at a higher level than my already of laid pipes I cannot raise the level of the pipes as that would mean redoing my entire kitchen from the base as a pipe is going under my kitchen. also i have a problem of seepage in walls and if i backfill or do any kind of filling to reach the sewer pipe then my foundation and part of my house goes under the soil. Currently the drain is at four feet depth and if i put my sewer pipe at the drain level so that all water gets drained then i will have to cut into the main drain at 2 ft from top so my pipe will be just 2 ft from bottom of main drain. Is it safe to do that as i do not want any water from the drain entering my house.