Here’s a picture of an interior window well drain. Sometimes when windows are below grade level on the outside, the well on the exterior will fill up with water and come in. When we are installing French drains, we can create a relief valve with PVC pipe so that if the water rises up in the well, it will drain through the pipe into our French drain directly. It will stop the well from filling up like a fish bowl and come in through the seams of the window.