As above. Got a 18'' storage main running from a drain chamber to a outlet pump chamber which has become silted up. Had a few goes with a vaccy tanker to loosen and remove the silt but only had limited success. The glazed pipe is probably too large to take a normal drain better to do the job, anyone know of a tanker based jetter which can pull itself though the pipe whilst clearing the blockage in the locality? Any advice/contacts from the resident land drainage experts would be great fully received!