When we bought the house there was quite a bit of standing water in the basement. We determined that there were two problems: 1)a leaky basement and 2)a clogged floor drain. After some advice from one plumber I dug a trench from one side of the basement to the other. Turns out I got some bad advice...and now the first plumber won't call me back.
So I called another plumber to finish the job. Since the trench was already dug, we ended up replacing 95% of the cast iron drain lines in the house including the 4" vent pipe going through the roof. How much did I need to replace you ask? Only about 25% - yes, that's correct we replaced 70% more than we needed to because of bad advice.