Click the Play button to See. This video shows the insides of a French Drain. Water drains easily through crushed stone, and falls to the level of the perforated pipe at the bottom of the trench. Because this perforated PVC pipe is sloping downwards, all of the water from the entire length and depth of the french drain will collect in the pipe and be discharged at the termination point. This video shows the volume of water that can be found draining from a residential property in New Jersey. The pump is in place to remove the water for the purposes of this video, and is not required for the water to flow through the French Drain. Click to Exit this page