Gravity drains only work when the pipe drops steadily along its length. Australian practice typically requires a minimum grade (for example around 1.65% for 100 mm house drains) so water moves fast enough to carry solids with it.
Too little fall lets solids settle; surprisingly, too much fall can do the same, because water races ahead and leaves solids stranded.
Keeps wastewater and solids moving through the drain under gravity alone.
Every gravity sewer and stormwater pipe is laid to a designed fall.
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.