So I have started digging my foundations and have come across a rainwater drain in the line of the foundation. Its connected to both my downpipes at the back of my house. Now will building control let me remove the pipes from the footings and then once the extension is out of the ground and going up I will then re-run the pipe work to new locations? It means for a while the rainwater drain will be in the floor but capped. The other side of the house downpipe I will put into a water butt whilst the works are going on.