Hi, my back garden drain takes the discharge from two household waste pipes and a rain water downpipe. Inside the drain there is a hole that seems to be the same size as the rainwater downpipe. My question is - could it be the case that the rainwater downpipe should be slotted into this hole (see picture of the orange in-drain fixture with the hole in it)? I know there is a soakaway in the garden as I've found the pipe, so I'm concerned that household waste is getting into the soakaway due to the rain water downpipe no longer being fitted into the in-drain hole, to both take rain water to the soakaway and prevent household waste from entering the soakaway. Any thoughts or knowledge on this would be very much appreciated. It's a typical 1930s terraced house in SE London.