For a truly deep understanding, study (drain and sewer systems outside buildings) and Building Regulations Part H (UK) or IPC/UPC (US) – these detail minimum pipe slopes, access intervals, and design flow rates that prevent blockages from occurring in properly designed systems.
Unlike a standard 32/40mm waste pipe from a sink, a soil pipe is typically 100-110mm (4 inches) in diameter. It connects WCs, bidets, and sometimes soil stacks to the main drainage system. Blockages here are critical because they handle solids and paper. unblocking soil pipes