Standards set minimum falls so that regular flows reach a velocity that scours solids along rather than letting them settle. When a drain loses that condition — through backfall, bellies or oversizing — sediment accumulates even without any single blockage event.
It is the engineering reason "the drain has enough slope" matters more than pipe size for keeping things moving.
Ensures drains transport solids reliably under everyday flows.
A design criterion applied to every gravity sewer and drain.
A CCTV drain inspection is the standard way to confirm whether this is what's happening in your pipes: the camera shows the condition on screen, a locator pinpoints the exact position and depth, and you get a recorded report before any repair decisions are made.
A CCTV drain inspection shows exactly what's happening inside your pipes — no guesswork.