Hi, I have a downpipe that runs from the gutter on the garage, into a paved area and I am unable to see the end of the pipe, as it goes underground. The pipe is blocked with debris, may have been blocked for years. I have pushed a copper pipe down it and the blocked area is below the ground. Dont really want to take up the paving to remove the pipe. Can anybody reccomend anything I can pour down the pipe to clear this? As you can imagine, with the recent weather, the gutter is now overflowing, ruining the lovely recently painted white walls :-(.