Holes on PVC piping can face up or down. We find many companies are still installing PVC with the holes in the downward position when installing a French drain system. Also, if you research this subject, you might find most literature states the holes should be facing down. Here is some info to help you decide. Remember this is not rocket science-its basic common sense. Picture a pipe in a trench and there is gravel filled all around the pipe. Now we place a garden hose in the trench and turn it on full force. Water will run through the gravel almost as fast as the water will pour out of the hose. Now let’s put a 2nd and 3rd hose in the trench. As there is a slight restriction in the water flow through the gravel, the water will eventually raise up into the holes in the pipe. Only clean water goes into the pipe and a clean system will last forever. Basically, a French drain can work if the trench was filled with gravel and no pipe is used but there is no benefit to eliminating the pipe. 

Information on Iron Ocher

On another note, what if the ground water had high levels of iron ocher??? (orange/brown deposit sometimes found in ground water) Iron ocher appears in 1 out of every 10 homes in the NY, NJ areas. It clogs French drain systems causing them to malfunction prematurely if a system is not installed correctly. When the piping in a French drain begins to collect residue, this clogging process starts at the bottom of the pipe. If the holes on a PVC pipe face downward and become completely blocked, a complete malfunction of the system is soon to follow. So, when installing a French drain, the holes in PVC piping always face the upward position. The only time holes should be in the downward position is when installing a leaching field. This is when water is poured or pumped into a pipe and we want the water to drain out of the pipe into the surrounding ground.