During days of heavy rain last April our outer wall in the basement let in water. The sump pump was not working but the pit did not overflow. The wall that let in water is on a slight slope that drains to the back. In the last year since the sump pump was replaced, with many days of heavy rain, the basement has been bone dry. What could have been the cause? The insurance company said it couldn't have been the sump pump.

The cause of which? You had a likely grading problem with water seeps through the wall before it ever reached your curtain drain. However if the pump did not work the water in the curtain tile around your footing filled up and could seep through the crack between your floor and the wall.