Tree root intrusion
Tree roots are the most common cause of blocked drains in Melbourne. Roots seek moisture and nutrients, penetrating even small cracks or displaced joints in clay, PVC, and earthenware pipes. Once inside, they form a dense root mass that catches debris and progressively blocks the pipe. Older suburbs with established trees and original clay drains are especially susceptible.
Grease, fat, and oil buildup
Cooking fats poured down the kitchen sink solidify as they cool, coating the inside of pipes and gradually narrowing the bore. Over months and years, this grease layer traps food particles and other debris, creating stubborn blockages that household drain cleaners rarely resolve. Commercial kitchens and share-houses are particularly prone.
Foreign objects and non-flushable items
Wet wipes (including those labelled ‘flushable’), sanitary products, cotton buds, nappies, and excessive toilet paper are frequent culprits in blocked sewer lines. These items don’t break down in water the way toilet paper does and can snag on pipe joints or existing buildup, creating a blockage that requires mechanical clearing.
Broken, collapsed, or misaligned pipes
Ground movement from Melbourne’s reactive clay soils, age-related deterioration, or damage from construction can crack, collapse, or displace underground drain pipes. A broken pipe creates a rough surface that catches debris and restricts flow. In severe cases, the pipe collapses entirely and must be replaced or relined.
Hair and soap scum accumulation
In bathrooms, hair combines with soap residue to form dense clumps that lodge in the drain trap and waste pipe. Over time, these clumps grow and harden, significantly reducing water flow. Showers and bathtub drains are most affected, especially in households with multiple occupants or long-haired residents.