TO PITCH OR NOT TO PITCH

One of the features of an Arid Basement Waterproofing French drain system that separates us from our competition is that we pitch the PVC pipe and trench to the sump. Most companies do NOT pitch the pipe and only go to a uniform depth of about 6 to 8 inches. These companies, in their literature, will state something regarding the footing (e.g., to the footing, alongside the footing). The reason for creating a downward slope to the pit is so the water is gravity-fed down to the sump and pumped out. In addition, that flowing water constantly cleans out the pipe because water doesn't sit in a tilted pipe. Creating a pitched trench clearly takes more labor, removing and replacing material, and know-how, including how to navigate the pitch around sewer pipes, boulders, etc. Some customers ask why there are companies out there who don't pitch the pipe. It's because it's simpler: less dirt is removed so less gravel is needed. But potentially system-blocking sedimentation can occur when water sits in a flat, non-pitched pipe.

Side note story: Whenever I inspect a basement that has existing French drains that aren't pitched, the place where homeowners almost always say they get seepage in is the opposite corner of where the sump pump is located. To me that completely makes sense, because it's the farthest point from the sump pump and the build up of groundwater can't make it around the perimeter of the basement (through the level pipe) to then get pumped out.
 

How you can tell if the pipe is pitched or not is by the depth and angle of the pipe entering the sump liner. Depending on the length of the wall or run, the pipe should be at least 8" (on a short run) or maybe as deep as 15-16" if it is a long run encompassing, say, 2 walls. Here are some photos depicting a non-pitched system versus a pitched system.

Here's our system, mid-installation, notice the angle and depth of pipes at the bottom of the pit.

Here's a job done by a competitor. Notice the flat, rather shallow pipe entering the sump.